I'm strongly in the camp of restricting Gitaxian Probe and Preordain and Gush. Restricting Gush alone will actually make mentor MORE of a problem, as people get away from playing low land counts and partial moxen, and move toward full artifact mana and play cards like Thirst for Knowledge or Paradoxical Outcome, and as such give themselves a much better Eldrazi/Workshop Match.
I have said for awhile that perfect knowledge of Gitaxian Probe is an issue. For years, I've played combo decks with Duress as my only disruption (In GWSx for example), and I would laugh at the double Force of Will + Mana Drain hands. A good player, given perfect knowledge, can play around your hand more often than not, and I showed this multiple times, including when I top 8ed the ICBM Power Nine tournament with GWSx and when I top 8ed Champs with Drain Tendrils.
Gitaxian Probe, while not stripping a card out of your hand, also reads "Create a 1/1 Monk Token. All Monks you control get +1/+1 until end of turn", ON TOP of being FREE, letting you map your plays perfectly (or near-perfectly if your Opponent has a draw spell and/or Top), replacing itself, AND being blue! The card is a Gitaxian Problem.
Preordain should definitely go on the list as well, because it's a crime to me that Preordain is not restricted when Ponder is restricted; and without Gush being restricted, there is no way Ponder comes off. And even if Ponder comes off and Gush goes on, without any of the other changes I've mentioned, nobody will want to play that format either as the 4 Ponder 4 Probe 4 Preordain find Time Vault/Key by turn 3 every game decks will not be enjoyable or skill-testing to play against.
Keep in mind, while I still somewhat like playing Vintage, I don't enjoy playing the same exact versions of decks 3+ times in a tournament; I also don't enjoy the fact that when my opponent can either just draw free cards and/or get perfect information at any time, it really closes the gap between top level play skill (which I'd argue I have) and the average/below average playskill of many vintage players, since the power-level of the cards significantly decreases the amount of time you have to react to your opponents good draws; the ability to make smart plays, plan your turns, and come back from a deficit with these cards is so much smaller than it used to be. I remember a couple cases at Eternal Weekend where during the game, I was even telling my opponent how to play their deck correctly, because it just didn't matter because they had turn 1Mana Crypt, Land, Mentor, Probe, Preordain, and Force of Willed my first spell, then turned on Gush into Flusterstorm turn 2 and I just died.
That example doesn't really outline the playskill point (which is more my opinion that more powerful cards give monkeys a better ability to win magic games) but definitely outlines the ability for these cards to just close out games way too quickly.