My one booster R1200 later, but looks worth it.
I ran the car with one booster connected to the front brakes and the rear brakes' pipes connected through a 3/8 x 24 female coupler. Test drove it over the weekend at progressively higher speeds and it seems as if there were no adverse effects in terms of balance or lock-up.
I also bought a brake and clutch bleeding kit at Midas for R60 and it was a revelation! No having to make the wife breakfast before she reluctantly pumped the pedal

!
So, in sum, gentlemen - it seems safe to run one booster at a time (I would suggest the front be boosted) and save up to replace the errant one.