Okay, I'm just confounded now.

Windows slow format in FAT32, power down and reboot n810, clone completely clean copy of Diablo (newly flashed, nothing in documents/images/etc), and after install tool finishes, booting into SD gets me back the files i had in the clone directory from before i formatted.

Except, instead of 620 MB or so of useable space, now i have 410MB of it. Where is all this junk data coming from... do i have a bad internal memory card or something?

A strange thing i've noticed is that i haven't needed to install install-tools more than once anymore. the first few times i had to reboot it inbetween 2 "installs" (penguinbait mentioned that it has something to do with the tablet needing to correctly remount the drive after newly partitioning it), but now it is capable of installing it straight up... hmm....

so something is being retained despite flash and formatting... maybe i should pull battery, flash, format, pull battery and try again...