Except that it doesn't work exactly like tape loops do.
I'm 100% down with the poster above that said you should probably look into an MPC instead. Just looking at cost ALONE points very strongly toward that and AWAY from modular, plus this build is sort of an attempt to build one (minus a lot of the useful firmware aspects). But don't take my word for it; let's surf over to Sweetwater and see what $1700 and change gets you...
MPC Live II = $1199
MPC One = $699 (you could get TWO of these!)
NI Maschine Plus = $1399
Elektron Octatrack mkII = $1399
Polyend Tracker = $599 (you could almost get THREE Trackers for what the build's modules alone cost)
Pioneer Toraiz = $899
Pioneer DJS-1000 = $1199
This falls into the "why you don't try and build a drum machine into your modular"-zone of errors. And the big error there is this idea that you can come up with something better in modular than an already-existing device has. Not...gonna...happen. Plus, any of those machines I've listed also contain the needed utility functions that the present build doesn't and CANNOT have due to the limitations of the cab.
Modular isn't a panacea for everything. This is another example of that.