i believe the newer digitechs come with sd card drives. but this requires an extra step of moving the media card to communicate between the device and a computer. i also have hope that the tc-electronic usb ports can be more useful than just downloading preset effect parameters...
i like the idea of midi footswitches, and i have no doubt getting fast at doing your looping in the DAW has more benefits for recording than floor units provide. for me the foot interface is what makes the difference in speed of layering loops. speed of layering is inversely proportional to the amount of other tasks your hands must do - manipulate a looping/computing device, switching instruments, etc. speed is useful for my fleeting creative moments (eg. will this baseline fit well with these two syncopated guitar parts?). having to use your hands for both playing and manipulating a looper slows the process, unless you are a drummer playing with your feet and looping with your hands
with a regular 6 string guitar and some sub octave effects or recording a double time bass line to slow by half (a feature of many loopers) i can layer guitars and bass without having to using my hands to switch instruments.
what it came down to when i bought a floor unit was the time investment it would take to work out the latency with an aftermarket foot interface and record with a system that reads and writes from a hard disk. i suspect these engineering problems have improved in the few years since i last checked, but i wonder if there are computer solutions optimized for ruggedness and price. how well will a standard notebook hold up under regular gigging use? what about instead of increasing processing and graphics power we invest in a trauma resistant housing for the computer? hopefully someone has already found this combo