As far as I know (I may be saying bullsh*t, someone please correct me if I'm wrong), ROMs cooked porting files and apps don't work very well on Defy (something to do with crappy kernel and locked bootloader provided by Motorola), which results in lots of FCs and general instability. building it from source, and porting only tweaks (like BRAVIA engine and stuff like that) are more reliable. It may be only with me, but, i.e., MIUI ported builds (specially MIUI v4 and higher) give me extreme instability, with FCs and hot reboot happening all the time (plus, permissions management on MIUI is not that reliable on every Defy build I tried). As I said, it's my personal experience, feel free to put my arguments to the floor.
