I could make an essay on why, but to keep it short -- it's just too damn good this time around. Many of the SL class abilities are quite lame, but then you have some very fun abilities that work in such harmony with our kits, spells like Abomination Limb, The Hunt, Hallowed Ground and many others. It's not too early or too late to speak about this so please don't bring up silly arguments like that, imagine SL is ending tomorrow and you have to forever say goodbye to these beautiful abilities. Beautiful, another reason I'm so fond of them, because compared to my big old fireball they look way more up-to-date and impressive.
I wouldn't mind it if class abilities of our covenant of choice became permanent. Balance is also a non-issue, provided some of them are tuned down a little. Classes felt stale, they still do to some degree but we desperately need new skills & effects, this much is apparent at this point.