Seeing the thought on running two Shoebox F-10s together for speed of fill, I though I would clarify that one shop compressor (and one pre-Shoebox desiccant dryer) would have no problem supplying the Air to both compressors simultaneously.
The Shoebox website says that you need a shop compressor that can put out 2 cfm, but that is simply a very low number that a) almost any compressor that puts out the 125psi air can meet, and b) allows for some downtime for cooling of the air charge. The actual flow rate used by the Shoebox F-10 is actually ~0.2 cfm (10 cubic feet per hour divided by 60 minutes) . . . . so pretty much any compressor that would work for one unit would support two.