@meadbert No. I agree you want fast dredge hate as well. I just look at your sideboard and see a different philosophy. if you want to consistently hit your specific hate i'd rock with a 4th jailer. but if you want to hit multiple angles and have a card that does double duty against p.o. i'm having a lot of success with ashiok.
i also think it should be looked at like other pw's in the format, most notably narset. even if you are playing only on color moxen, you are dropping it t1, or t2 some % of the time off of mulls and/or cantrips.
Before adding cage or a 4 yixlid jailer, have you considered Ashiok, Dream Render for the sideboard? He has been very strong for me in control/fair blue builds, doing major work in both dredge and in slowing down tinker - citadel combos in P.O.
I'm even going to start testing him maindeck in some of my landstill lists.
I just think he's a very wide, one sided powerful card that maybe had a little shine taken from him bc of narset.