Well, this has 2 sides.
Slower mind control = Masterminds cannot capture T3 army that fast, but then they are also easier to control for their owner, as a single Mastermind won't overheat that quickly. So, T3 units will be easier to use against Masterminds, but overwhelming with low tier units will be even harder, if not impossible. Sure, you can still spam T1 to deal with Masterminds, but if there are other units to shield them from damage, then using them during a battle is trivial.
Faster mind control = Masterminds can capture a T3 army in a moment. However, that means 1 Mastermind will capture any kind of army in a moment, and thus, preventing overheating will be harder. So Masterminds become a counter to T3 armies, but can become uncontrollable when facing a T1 spammer, and the player has to constantly watch them. If they suddenly get near a bunch of infantry, then it's instant overload.
In the current state, i think it's neither of those extremes.
Edited by mevitar, 03 December 2014 - 03:24 PM.