The setup that you mentioned is supposed to be a good setup, but if you are just trying to save yourself some money on the Quark by going with the MGM, I think the consensus around here would be to spend the money and get the Quark. Did you ask Mike what it is that he runs? Quark/Neu.

Do your research on the Compro before you pull the trigger. If you like to run with reverse, you might want to go ahead and get the Quark. Many on this forum have said (and I've experinced it) that the Compro has a quirky reverse and most just disable it and run forward only. If you do get the Quark, you will have to make provisions to keep it cool, like mounting it to a heatsink, which Mike also sells.

He's told me that he's run his setup for literally hours, battery pack after battery pack in 100 degree weather, without thermal issues.

Personally, I'd either go with the MM/Feigao setup or the Quark/Neu setup. If you go the MM route, you could always upgrade your motor later. Castle will come out with the fix for the 4 pole motors sooner or later and besides, you could always just go with a Lehner. They also have to become available sooner or later. Believe me, there is absolutely nothing wrong with a MM esc. I'm running mine on 5S right now in a 13lb truck with 40 series tires and it is absolutely insane. I couldn't even try to run it on the track. I'm thinking about getting either a 9XL or 10XL for racing.