[MetalMan]

Currently there aren't any MT controllers that can run brushed and brushless. There are only the smaller 1/10 controllers that can do that. The one that will be coming out in a few months that can handle brushed and brushless is the Mamba Maxx. This would run 2 brushed motors just like the EVX would.
Brushless motors generally are less affected by dirt,as long as you have the rear bearing covered up with a piece of tape. Besides the front bearing, they are sealed up.
Brushless controllers in general are probably more sensitive to water, and are much more expensive to replace from damage done by water.

IMO, it would be best to save the money that you would spend on brushed so that you can jump to brushless. Sure, the initial cost is higher, but later if you would plan on going brushless, you would end up paying more overall.