Given altar preps still work, I don't really think that's true except for purist. Binlor is phenomenal because you can boost your MR up and then convert out once you're down, GG prepped can be extremely strong. Once you get to purist it's more limited.
Speaking strictly of altar unlocks, though, there's still little reason to unlock him in the bottom level rather than just convert out directly to someone else. JJ would be the better example of being worth the unlocking charge if you prepped him on the surface.
Rogue nerf? What Rogue nerf? The GG + Orc Rogue combo is still just insanely strong. (Other than scumming for GG's altar reasonably early, the main challenge is inventory management. )
For the record, that's now every vicious dungeon except Naga City (which doesn't permit this strategy on a purist run, for obvious reasons) and the Tower (which may or may not be possible - I've never actually made it to Horatio with this strategy without GG crashing the game ).