There are three main changes to Abandoned and Alone -> (Advanced):
- 3 horror instead of 2.
- Doesn't remove weaknesses from the game.
- If nothing is removed, shuffle it into your deck instead of taking horror.
The first is rather obvious in impact, and will usually be the most relevant. The second mostly means you can't cheese away other weaknesses and is bad, but primarily relevant if you're cycling through your deck again.
The third is actually somewhat mixed. With the original Abandoned and Alone, if you had an empty deck you would keep drawing it over and over until you die. Including the horror from drawing from an empty deck, that's 3 horror every turn. Given that it also removes cards from your deck from the game, it could result in an accelerated death spiral. Unlikely, but possible. With this version, if you never have anything to remove, it always shuffles back into your deck with no effect. You'll therefore never draw from an empty deck again, which also means not seeing your other weaknesses again. It will still eat up a draw, though.
Of course, if you have either Wendy's Amulet|(Advanced) in play, all your events will get shuffled back regardless, so you could simply cycle through some number of events over and over, never again drawing any weakness already. And if you hit the original early, you could get away with exiling nothing but weaknesses. This one you can't avoid that way.
Overall, significantly worse, harder to cheese, but you can possibly delay taking the horror indefinitely if you need to (by having nothing your discard pile). The question is: Is that worth being able to play non-top events via the advanced Wendy's Amulet?