Hi sixwheelbeast & all,

Problem solved. With a second hand N900 (but used only for phone and music) luckily found on a local eBay near me.

I flashed, copied my backed up data and reinstalled KP, CSSU and all apps (not via the default Restore Settings and Restore Applications, to be sure I have something clean) as I had before, and feel it's going much faster.
Well, I hadn't done any flash in 2+ years. But even when comparing the speed of the 2 just flashed devices in opening the default apps, the barely used one was faster.

I hope you manage to solve your problem (or get a spare device when the opportunity shows up).

jb

Thanks for reporting back.
So far I have not had any reoccuring problems, fingers crossed.

Do bare in mind your old device is not completely useless.
Development can be done with it via USB and MADDE etc.