One of the major differences with Ratcatcher is getting over the impulse to trash ASAP. If it misses the shuffle, you want to wait to trash with it until either you kill your worst card (e.g. Hovel), or you would risk it missing the shuffle again (e.g. you have 7 cards, including a Smithy, left in deck). You absolutely can benefit from skipping a trash on T5 to get a $5 and still trash on T6 most of the time.
This also makes it a good fit for triggering on-trash bonuses, most notably Market square. While it is annoying when you are trying to kill the last few coppers, it is very handy to double the odds of lining up trashing & Mrksqr.
He works surprisingly well with other trashing. Even a delayed cantrip does not hurt Steward or Salvager trashing and you can leave his trashing ability until another turn when you end up with things lining up badly (e.g. GoldGoldEESteward). Remake seems like a very nice option here - clear out some coppers, eventually dispose of the Remake, and help Remake more quickly go Estates -> Silvers -> Remakes -> $5s.