oh, and the differences....the jamman supports uploading of larger files to the device, whereas the 20xl essentially has a line-in port and you can just record CD's/mp3s like that. i heard that the jamman was harder to get a good loop going because the quantatizing skills of the jamman are less than impressive, but again...i've never actually used one. i do know that the quantatize feature on the boss is great, it detects what tempo you're playing hte riff at even if you don't set one beforehand, and it makes (for the most part) very accurate cut-off points regardless of if you hit the "stop" button a few seconds late or whatever. sortof takes your mind off getting the loop tempo perfect and you can concentrate on making quality music instead.