Another sort of un related option would be to go ahead and use the laptop but to get some sort of multi channel vst host virtual mixer type software, run ptw using mme drivers (or possibly through the virtual mixer using virtual audio cable) and have everything mixed all on one laptop ( live guitar.. usb controller keyboard & live vocals and ptw backing tracks)...the ultimate goal I have is to get my setup time down for smaller gigs & to get my amount of gear I have to haul minimized....right now Im @ just under an hour setup...a 5 min setup would be great...and I think can be possible with technology as it keeps advancing:)

...........Jeff......