It was a Guru with PF30. It came loose after about 1 test sprint on the street outside my house. I was able to remove it by hand. Guru said the frame was in spec even though 3 different mechanics at 3 different shops weren't able to get it secure. The only solution was some sort of epoxy/glue/loctite to affix the cups in the frame. I really didn't want to do that as there are potential maintenance pitfalls down the road. Guru was good enough take it back and build me a replacement with a threaded BB shell. They have a heavily knurled Al shell that they are able to wrap in in such a way as it is highly unlikely to ever break free.

I recently bought a steel framed Cyfac and, after my previous experience with press fit (and getting similar feedback from several local shops, including a Sarto dealer and another custom frame builder) decided to just go with threaded and avoid all the potential trouble.