The "per manufacturers specs" is VERY misleading IMO. It doesn't take into account the entire circuit (having FETs rated 10,000A doesn't matter if connected by a 20GA wire), temperature derating, thermal management, whether they are lumping all FET ratings together (which is wrong since only 1/6 are carrying the full load at one time), etc. Judging by the FET count and part used in the regular MM (original one) vs the ones found in the MMPro (better FETs, just fewer of them), I would say they are rated for around the same current. The RX8 is roughly equivalent to the MMM current-wise.
If you are pulling enough power that the 13ga wires are to small then you probably will have bigger problems. The MMP will hit its current limits before the 13ga wire does. So if you think that the 13 ga wire is to small for your application then the MMP is also probably to small for your application. Look at the MMM or RX8.
I can't decide if its more fun
to make it...
or break it...