Ok so what I have is a retail unlocked black R479 (DAP) V3i B/L 0A.52. After much thinking, asking around (thanks promaja), and research, I finally flashed the sticky F/W. I believe this hasn't been really confirmed before so I just took my chances and bought a 2GB microSD for the test. All I can say is, it was well worth the risk!
Here is the official firmware with unbranded stock flex from Motorola:
Not really "just SanDisk". As I also mentioned, you can also try TOSHIBA. I was using it before for 1GB and it worked with no problems, so there are high chances it'll also work if you use the 2GB.
These are only "recommended" brands (tested to have worked), but it doesn't mean it's limited to that. You can also try others and maybe expand the compatibility list.