[jsr]

Some people run the MMPro on 4s in a 1/8 buggy. Temps stay pretty controlled around 130-140F with the fan on. Once the fan is off (either you disconnect it, which there's no reason to do so, or it breaks), it will thermal pretty quickly. On 6s, it consumes much less current and will run cooler ONLY if you run the appropriate motor.
I did my first conversion back when 1/8 brushless was somewhat at it's infancy. Back then, it was recommended to spin the motors to similar rpms that nitro engines ran at (typically 35k-40krpm). At those rpms, motors run hot and runtimes suffered. Now, we've learned more and learned to run brushless motors around 30krpm, give or take a few krpm. That's partially because electric motors make more torque with a broader torque curve than a nitro engine. Keeping that in mind, in order to gain the advantages of cooler running with the MMPro and 6s, you NEED a motor that will spin around 30krpm on 6s. The 2200kV won't do that, so you likely won't be able to run the MMPro with the 2200kV on anything higher than 4s, and even then, the Neu-Castle 2200kV eats a good amount of current, which may still thermal the MMPro even with the fan on, or at least run it fairly hot (160+F).
As with others, I'd recommend an MMM instead (MMPros are popular right now and you should be able to sell it).