I've had a few issues with B7 as well, particularly with antialiasing stalling when you return to a render to finish it off, but that bug has been reported and I'm assuming will be fixed in the first SR. As for importing human figures, clothed or not, I stopped using DS to do so. For me, the DS/Bryce combo has always been a bit of a train wreck in that regard. I export from Poser as an obj and B7 imports flawlessly.

B7 has never crashed or run our of memory for me while rendering large files, but I've found, as duo has, that using the new lights (Fill, Dome, etc) will slow the render down to a virtual stop, and I'm running the program on a dual core iMac, with all background programs off.