
A lot of people are looking at the new Pod HD500, which is pretty much the M13 with amp sims, a built in expression pedal, and a different interface:
http://line6.com/podhd/hdmodels.html
A lot of the guys on U2soundforum have even switched from M13, or even their Axe-FX rigs, or pedal boards, to this unit. It seems to suit their needs better than anything at the moment.
Hope that helps,
Alex