Huh. What version of massstorage.class do you have, and how is it configured? I assume AmigaKit had you do a complete clean/removal and reinstall of the software? Do you have the A1200 version of the RapidRoad (that comes with the acrylic case, removed for use with the X-Surf 100) or the standard version? (Their firmwares are different)
What format/size/brand are your USB sticks? FAT/FAT32/NTFS should all work, if you have FAT95 and NTFileSystem in your L: directory.
For what it's worth, my RapidRoad has got to be one of the most fool-proof things I've bought for my Miggy. Sure, it has it's issues, it chokes up if I daisy-chain too many hubs and doesn't like some brands of mice, but overall it works well.
I submit for your amusement, this picture of mine with two hubs plugged in (one in the monitor and the other one daisy-chained into that), three USB drives, a keyboard, and a mouse, all plugged in.
Also a pic of my massstorage prefs. Do yours match?
(Edit - added a pic of 2nd page of prefs)