Nick...
My personal preference is to use the USB Flash Drive (thumbdrive), for a couple of reasons.
1. As mentioned, the SM card is somewhat fragile and needs more TLC than a thumbdrive (pen drive, memory stick, etc.)
2. I heard, but have not documented, that the SM card life may be limited to 10,000 accesses.
3. I have been teaching some other 3K users locally and have found it very convenient to use my thumbdrive when working on thier keyboard (portability of my my files for use in other PSR 3000s)
4. Since I don't have a card reader, I backup all my files in several places:
A. My PC (stationary backup)and a zip drive.
B. A second thumbdrive (portable backup)
C. and on the Smart Card, which I never remove from the keyboard.

I have noticed no signifant difference in access time between the SM Card and USB Flash. Both load lickety-split.

I have been using 128MB and 256MB in the USB and have not detected any difference. Even with the tons of files I have loaded, including .sty, .mid, multipads, external voices and tweaked settings, very little space is used, even on the 128.

Eddie