We have been running the old 3.0 adventure from WotC , "Heart of Nightfang Spire". The module itself is very mediocre imo but we're having fun running through it. Converting stuff to PFRPG(b) from D&D3.0 is about as easy as converting 3E to 3.5. The biggest "bump" was monster DR , which is also an issue for 3.5 games. Oldstyle stat blocks even have the CMB listed for you, since it is listed under "grapple" bonus.
Sofar so good.