I absolutely love my Corsair Flash Voyager GT 4GB..... I only use it for readyboost, and the occasional BIOS flashing though and some other storage of things. But it works like a charm and is one of the fastest drives I have used.
Check out this review Grace did, it might be of some help
DH Review: 19 Flash Drive Roundup
The performance review of the drives are probably what you want to look at. The GT was not included, because at the time I believe Grace thought it was being discontinued, or could not get ahold of it.
EDIT: For comparison (its not same version of HDtune.... but check it out)
Thats my VoyagerGT, it has considerably better minimum transfer rates, and access times in comparison to the normal Flash Voyager.