Have other Gush pilots found the [DPS vs. Mentor Gush] matchup difficult? I'm curious...
From the results we've read online, and the testing I've done with DPS vs. UWR Mentor Gush it has been about a 50/50 matchup, depending on deck configuration. The more Defense Grids you play main deck the better the match gets for DPS, as it invalidates a lot of the soft counters that Mentor and Gush decks rely on. Things like Xantid Swarm, Thoughtseize (takes opposing hatebears, TKS, and never misses usually make it worth the life), City of Solitude, and even Mind Twist (doesn't get Misstepped, and is better against more decks) are also very good tools for DPS and Gush Storm decks at the moment.
Yeah, in testing I've had the matchup fluctuate from 40-80% depending on deck construction. Counterbalance is one of the more hateful options against Combo, but even less extreme measures like Cabal Therapy and Snapcaster Mage can shift the matchup dramatically in Gush's favor. It's funny, the more anti-Gush cards Storm plays like Xantid Swarm, City of Solitude, and Defense Grid, the less consistent it is at actually winning the game, which creates a sort of limit on how bad the matchup can be for Gush.
I split my two matches against White Eldrazi (punting one of them) - Adding Mystical Tutor and Balance to complement the Walkers and Swords is pretty strong. Mindbreak Trap also can do work against their most broken openers. Alternatively, JVP is quite good if you can get him active, Baleful Strix is quite strong against them. Gush can definitely be built to beat Eldrazi and the Gush decks that did well made the necessary adjustments. That doesn't mean that Eldrazi is not a powerful deck - it certainly is.
Jaco's version is likely much weaker against Mentor. The reason White Eldrazi has a strong Mentor matchup is the combination of Spheres and the big threats. Without the Spheres, Mentor can just go nuts and the deck is more susceptible to Supreme Verdict, which commonly sees play out of Mentor SBs.
To give you some tiny data, I went 2-0 (4-1 in games) against UWR Mentor Gush (both having a small Bomberman package) at NYSE4 with Unpowered Eldrazi, and thought the match was generally in my favor against Gush decks of all varieties heading in to this tournament after having tested the past few months (which is why I simply couldn't justify playing 4C Mentor at NYSE4, which was my other deck sleeved up and ready to register). Null Rod and 8 Wasteland effects function similarly to 8+ Sphere effects. Balance can be very good against Eldrazi, but often comes priced in with losing most of your hand when casting it against an Eldrazi player who usually has 1-2 cards in hand. I believe I had my board reset by Balance, Engineered Explosives, and Toxic Deluge at NYSE4, and it didn't even seem to matter in any of the games. Eldrazi Mimic plus one other resolved follow up threat is usually enough to finish off your opponent in those situations because of the damage already incurred before a sweeper is cast. I remember beating Oath in a fun G3 after he resolved Deluge to wipe the board, then I cast an uncounterable Mimic and passed, and then I cast another large (non-Reality Smasher) creature the next turn, triggering Mimic, and the game was over.
Honestly, we didn't have you as playing against "Gush Mentor" once during the event. AJ Grasso's Gush Bomberman list was classified as "Other Gush" as we felt it was more of a Bomberman deck with only two Mentors and the Trinket Mage/Salvagers package. It didn't run Missteps, Preordains, Gitaxian Probes or even Ponder which are commonly associated with Mentor Gush. John Leone was playing Bomberman with zero Gushes and 1 Mentor. These aren't the type of decks that I expect to give you trouble - to the contrary, your null rods should be devastating.
The specific strategies I discussed were more oriented at White Eldrazi. You will note that I never mentioned Toxic Deluge as I think that card is terrible - you can't afford to pay 4+ life to wipe the board against a deck capable of deploying uncounterable 5/5 haste tramplers. Balance was discussed specifically in the context of Sylvan Mentor. It by itself is not enough - you need something like a Sylvan Library or Planeswalker (or Mentor + Gush) to follow it up. A strategy I've found that works well is to aggressively Gush before Balancing to maximize the Armageddon effect of Balance - Eldrazi does not function as well as Shops on 0-1 lands.
The main path to victory for Mentor from every playtest game I had was if the Mentor decks get a very fast start against any form of Eldrazi (ie. resolving a Mentor before Eldrazi or Workshop deck does anything relevant), but barring that they are usually on the back foot most of the game against the versions with 4 Cavern of Souls, as there is effectively zero working countermagic at that point, and even having 4 Swords to Plowshares is not usually enough to save you. Dark Confidant, JVP, and Young Pyromancer are all OK, but none really seemed to swing games like a turn 1-2 Mentor racing. The fact that dedicated Eldrazi decks are basically half creatures, and keep pumping out larger creatures makes it very winnable for both Tribal Eldrazi and White Eldrazi. Endbringer or Eldrazi Displacer can clean up the battlefield very quickly against Mentor if the board is clogged. This also ignores the ability for any deck to play Dismember, which matters more than you'd think.
If you have an MTGO account, I would love to test the matchup against you. But that was my point...without the Spheres, Monastery Mentor can trump your 4/4 and 5/5 Eldrazi by itself. I'm not counting on Swords killing all of your creatures, just the problematic ones like Displacer and Endbringer while negating the vanilla beaters with tokens galore. I've beaten quadruple Reality Smasher draws with a single Monastery Mentor on MTGO. Again, I'm happy if this thought is incorrect, but that has been my experience so far.
Mentor certainly can (and will) adapt to the results of the last month, but I think the other decks will keep adapting as well. I know I will (both with Eldrazi, and all of my other decks). I have read consternation about Gush (and Workshop) decks occupying a certain varying percentage of the metagame, but I can honestly say this is the most open Vintage has been to me since like 2002-2004, if people will take the time and put forward the effort to innovate, and I'm way more excited to play Vintage now than anytime in the past few years.
Jaco, I knocked LSV out of the VMA Championship event with a Magus of the Future combo deck. That deck ran Helm of Awakening and Fact or Fiction. I put forth a lot of effort into building a Nongush Blue deck that can compete consistently with other Gush decks and the field at large. So please don't make condescending remarks like "if only people would take the time and put forward the effort to innovate"... You don't know what people have or haven't done. It's a lazy argument and it really doesn't help with the discussion.
We all know Monastery Mentor and Gush are synergistic and the best of breed/most efficient at what they individually do, but there are Thirst, Gifts, Landstill, and other combo decks out there that can be competitive in this metagame, and you just have to put the work in to tuning them.
Gifts? I haven't finished going through the NYSE decklists but I'm not even sure there was a single copy of Gifts Ungiven present. Other blue decks are competitive? They were 16% of the metagame. And 0% of the top 8, 0% of the top 16, and 0% of the X-2+ decks. With Dave Kaplan actually beating Nick Cummings in the last round, there wasn't a single deck in the x-2 bracket (down to 22nd place) without Thought-Knot Seer, Workshops, Gush, or Bazaar of Baghdad. So forgive me if I don't see this metagame as wide open...