I found it a bit disappointing that all I got out of it was a non-cutscene dialogue option with them after I defeated the Hag, not even so much as a 'thank you' from any of them. In fact they acted rather brashly unfriendly which I found jarring, considering I could have just killed them instead.
I don't necessarily expect a full on proper dialogue, but a little optional reward for not killing them would, in my opinion, be nice. Maybe something simple like a minor magic item or some gold would make that more worth it.
If you damage stack Ethel in her hut before she runs away the masked people become friendly and have unique dialogue, you can even meet them in Baldur's Gate in Act 2 later.
Unless you pick a certain dialogue option with the Mask of Vengeance (I think it was telling him Ethel is dead) which causes him to flip out and then ALL the masks aggro you again...
