I will install the reservoirs soon, too, but I'm using all three because having separate reservoirs for front and rear brake master cylinders creates a redundant system if one of them fails/leaks.
At least the other one gives some useful braking. I'm I missing something here? Yes, there is the balance bar but that is a mechanical connection outside of a leaking/failing master cylinder circuit,
whether front of rear. Let me know what I'm missing. Thanks!

(can't seem to access the attachments)