I've finally started my CW campaign! In fact the party has just hit 5th level overall, and stumbled into level 7 almost by accident after sweeping the troglodytes from levels 4 and 6 (FYI, Oracle of the Heavens is sick and wrong). They have yet to find A'quilya or the library, but they've cleaned out all of the Clockwork Academy.
Of note, the mephits have been busy behind the scenes instigating trouble. After the party's second pass through level 3, having distinguished themselves as a real threat by cowing the orcs (all Drugila's remaining followers have retreated to the cloud giant tower, while Kaernga's tribe has been wiped out completely), the duergar simply dispatched Grime to have the orcs seal up the entrance to level 4 once the party passed by. Which they did.
After wiping out the better part of both tribes of troglodytes, out of spells and healing and a few of them sporting single-digit hit point totals, they fled back to the stairs, only to find their way blocked by a massive pile of stones against the door. Oh, the look on their faces: priceless!
Anyway, they found the pipe organ room and holed up there in secret, explored the Academy then returned to wipe out Sossank's tribe, chasing off most of the rest of them. They've discovered the entrance to the library behind the stonebore ant colony but couldn't figure out how to open the door (they are *this* close, they just haven't figured out that the books from the Clockwork Academy are what they need).
Then they discovered the access point to level 7, fought/diplomacy'ed their way past Vulgaris and the derro by the elevator, survived the skum ambush and are about to light upon the shore of Nall'loth's camp, where hilarity will ensue.
I've found that in some cases merely applying the simple advanced template to a monster was easier than trying to work out Warrior levels for some monsters, but indeed there is a fair amount of work required when converting monsters with class levels from 3.x to Pathfinder, especially when dealing with classes like sorcerers.