I think Treasury is about at the right place, as a card that is a bit too slow on some boards, but can be really nice on others for consistently hitting $4 or $5 instead of $3 or $4, which can be a huge difference. I wonder, though, does Treasury really do better in Colony games? The paltry +$1 doesn't seem to be worth going after when you need to hit $11, sort of how a lot of terminal silver actions lose some power in Colony games. Sure, you could buy and stack a bunch of Treasuries, but decks tend to be a little bigger in Colony games, so once you've gone green, it could be a while to line those Treasuries up again.
Also, I see people say watch out for discard attacks with topdeckers like Treasury, Scheme, or Alchemist, but it's really only necessary in games with discard attacks AND some form deck inspection (reveal top card of your deck). Unless a reveal forces a shuffle, it doesn't matter if whatever you're trying to topdeck winds up in the discard before or during your opponent's turn.