I did some compile test of Qtopia 1.7 a while back for my c700. I had a decent rom working. I used the OPIE patches (OZ ones too) to patch against it. Well the result was not that good thought. I was able to boot and see the GUI, but my touch screen was messed bad, everything was slow as hell and was bugged. I never had time to redo any test thought. There was a lots of work to be done so I didnt wanted to made a big project of it It was more experimentation !
But, I believe its possible if someone take time to hunt down a couples of the problems I had, etc.