Only downside is you cant read real amiga disks. Plain and simple thats it. Well you cant runn PPC stuff as well, but there isnt anything PPC you need to have anyway. Thats why I got a Pegasos. With a Catweasel II PCI card you can hook up a floppy drive and read amiga disks through UAE, and even use a real Amiga keyboard. I'll be putting two on order soon. One for the PC and WinUAE, the other for my Pegasos II.
