Weren't there already two "non-typical" drow off-shoots as it is - the followers of Eilistraee (dedicated to re-emerging to the surface and making up with the rest of Tel-quessir) and of Vhaeraun (the patron of the male drow)? And there were already quite a few more surfacer drow during the Spellplague times which weren't exactly bound to their supposed religion in any way.
As far as Drizzt goes, wouldn't the only clearly stated "rarity" to him would be his purple eyes which he almost got murdered at birth for, and most of his upbringing and how he became the way he is is mostly thanks to Zaknafein's mentoring?
