Well, according to the sim if you take a P6 BiS Paladin Twister and run it through a Vael fight, with just self buffs (no WBs, consumes, ‘other class’ buffs). You get around 2k dps.
Take a P7 BiS Paladin Twister and run it through the same Vael fight with the same buff state. You get 4.6k dps.
Basically, twice as much dps. The question is will “twice as much” make Crypts easy enough that people will run it, presumably for Reals. Since there wouldn’t be any gear in there for a Naxx-BiS raider.
Personally, me, I’d just run the vanilla dungeons and get my ~64 daily Reals. Or hit up an H1 MC (most of WGs MC Real farms are H1 for fast clears).
Which means, anyone ‘late’ will be trying to get into Naxx PUGs with 5/8 Sanc. gear (3 physical + 2 phantom from the set bonus).
Tell me. Are you going to take a 5/8 or a 8/8 in your PUG.