I like it!
So Midiflow is your Midi Router/Processor, and this makes AUM "just" the host/mixer, a powerful combo with great flexibility, kinda ingenious - Great thanks for sharing!
Just did a simple set up here, input from my midi interface (Volt2 as I use for the iPad Sound/Midi, gives me analog input for other stuff I want too when I travel), then a processing unit, and then I create a virtual output, which then is used as input in AUM, clever!
Found a bug though in the velocity remapping tool, using the "shape" curve, the one with the "dots" you can pull your own curve in, the furthest to the right, fiddle with it, and then press "reset curve", and the curve window goes blank... only way to get the curve tool back is to back out to the processing main "menu" and reset everything...
But this is definitely a very powerful solution!!