Not to be a Grinch but it seems like a lot of money to just change wires coming from your bar to one vs a bundle of 6 that can be easily trunked together. What concerns me too is that one of these things that is being multiplexed is the kill switch. Firstly, this unit can go bad, and who's to say that it won't start sending the kill-switch pattern when you hit the turn-signal - worse, in an accident it could fail all together and your kill switch function stops working - bike still running on top of you in a ditch...
What you've basically done here is created a single point of failure for all your front end electrics. If it get's fried by a power surge on any circuit you just lost, lights, turn, start, kill and horn in one shot...
A little clarification on your concerns:
Each function is separated into different fused circuits at the M-Unit. The M-Unit has an installed Starter Safety Motor, so thats as reliable as an external. If the M-Unit were to go "bad", it would be analogous to a fuse block melting. Bypass the M-Unit by jumping the switched 12v to the AUX output and away you go. you'll have limited lighting, but your bike will run. You could add the LIGHT circuit and TAIL to this temp bundle to get you home in a pinch.
Each circuit automatically resets in the case of a fault, so there is solid state redundancy and protection built in that is not available in 30-40 year old technology.
A significant difference to using an M-Unit versus stock switched loads is the handlebar switches see no load; they only send functional signals to the M-Unit (ground) and the M-Unit then transfers power directly to the component. This limits the resistance seen across the wiring, reduces the wear on switches, and allows much smaller gauge and fewer wires in your bike.
I'm not a fan of the M-Button as it has requirements for installation and can be problematic
with certain ignition systems, but it is a handy idea. I've installed 10s of dozens of these on all types of bikes. I have yet to see one fail and with the added safety/convenience features, they are a very nice upgrade to an older bike.