Thanks for all the responses!
I've got CSSU Stable (lacks many features from CSSU Testing), & many black magic placed on my device. Also introduced a weird defect due to all the black magic. I don't quite have the confidence that a direct upgrade will work that well; besides, I wanna get rid of that defect.

Understanding your stuff here potentially helps me avoid pitfalls when using my black magics in my N900

kh