Are any removeable from your keychain?
As an IT consultant I frequently have to connect my flash drive to people's computers and (so far) I only need my one 'master' drive. I must be the only person who cares about this, but I carry my drive on my keychain and don't want to have to leave my keys hanging on someone's computer so I only buy drives that disconnect from their lanyard/attachment. I originally used the Lexar Jumpdrive Sport, now I use the Lexar Firefly.
P.S. I second (third?) the idea of including a generic flash drive for comparison. How much extra performance do these expensive drives really gain you?
P.P.S. I know my Firefly drive is really slow, but it's CONVENIENT.