Ok, so I can hold off on the shop until later, it can actually be ignored and does not disappear if you don't take it. So, that's ... decent.
The "You get an extra choice of doors" never actually seems to do anything, and even if it did, ... you still have to go through them all.
It would be nice if the shop keeper, other than giving you a warning about the shape changing nymph, might actually give you some helpful advice? Or, is her "the only winning move is not to play" supposed to tell us that we are doomed before we start? :-)