Point taken :-). I'll get around to buying one, hopefully after I get this power drain problem out of the way.

Meanwhile, I have taken apart my N900 and inspected the flex contacts, and they look alright. I did discover (and fixed) an unrelated hardware problem. The miniscule magnet under the kickstand was missing, which caused the SD card to fail everytime the stand was engaged (made this connection thanks to several posts on this issue, here). Took a good couple of hours of filing and sanding a magnet to replace it. Works good now.

To verify the powertop/zzztop inconstencies, I flashed the device to stock firmware and ran three repetitions of powertop and zzztop, alternatively. As before, the results differ. I repeated the process after flashing again, and a fresh setup of CSSU-Thumb. Again, the results differ. Attaching the results from CSSU-Thumb here.