Converting geometrically stable SU models appears to be exceedingly difficult, at least using the methods myself and UT have been experimenting with over the past few days. We've seen crashes at just about every stage in all programs that touch the exported model. This is mostly because of the way SU exports geometry, and it's complete lack of support for good object grouping. :\
It also appears to export all sketch lines you draw as separate subobjects too - edge and vert groups that have no faces in them, and as such will crash all kinds of things. If anyone has done more than one successful SU->POF conversion, what process did you use? Please post it, because otherwise a lot of people are going to be stranded once they finish their model.
I'd very much like to recommend SU to new FS modelers, but at the moment I can't because of that crappy export process.