I have my A2000 set up that I can transfer files via either CF, SD, or USB. All my PC's have media card readers too. Think I use SD the most, honestly sometimes forget I even have USB even though the plug is right there on the side of the monitor, LOL.
I think CF & SD solutions may be a little cheaper than USB, but like you said, USB gives more options. 
I have look in to this..I'm fine with just an SD reader..
Is Amigakit the source for this type thing??