Well, it looks like it's time for me to give up again (for now).
Whether via uShare or FUPPES, my fully-firmware-upgraded PS3 just won't recognize nearly 90% of my files. (Most of which are AVI/XviD/Divx). It also doesn't really play much else, either, and depending on the version of the DLNA server software I use on my linkstation, I sometimes have more/less success.
FUPPES seemed to be promising, but the .cfg file how-to sites didn't match the version of FUPPES that optware installs. (In other words, it doesn't offer support for the PS3-specific section of the config file.)
uShare seems to work a bit better, but still has 100% failure with any avi or mp4 files.
Those very same files play perfectly fine via USB plugged into the PS3.
I don't know what else to do.
uShare via optware is at the most recent version, but FUPPES is not. Can I somehow upgrade FUPPES to the newer version that supports the newer config file, or will that involve compiling it myself? (Something I don't want to do, as this SHOULD be possible via stock Linkstation firmware)
Any suggestions would be amazingly appreciated.