After listening to it through my AKG 271's I will say;

Track A "feels" richer, slightly brighter, slightly crisper and more present. B sounds like there might be a very slight blanket or dulling on the sound. SLIGHT. It may also be my mind playing tricks.

But know this, they both sound fantastic, and any competent mixer would be able to work with the MPatch in the signal chain. Do I think that the controller is affecting the sound? Yes. Think. Maybe. But would my mixes suffer by having it in the chain? I highly doubt that. The slight dulling you may hear is only relative to the slightly less dull track A. That does not mean track B is dull, actually it's far from it.

People get too caught up in the measuring and quantifying of these things. The track itself sounds wonderful and that is due to many things taking place before it hits the D/A and the MPatch. If one controller is twice the cost and 5% better, I'm going to go with the cheaper one, and ideally the one that has the features I want. Unless the device is degrading my sound in a very serious fashion I'm sure I'll be able to listen through it.

The only reason I wouldn't use an M-Patch is I would prefer something rack mounted.