I've tried mediums so many times, they usually suck...and I'm in Texas, you know it's hot....
I've used both tires, and the pro lines are square and the impacts are rounded so the impacts get the nod, less twitchy....They both last the same, not really long, and the aka rims are better and the rubber stays glued to them.......
I try to use enduros unless it's just freakin slick, then I will switch to impacts...