I don't use the MD a whole lot, or the AR. I tend towards SMG's or scrambler pistols myself. And as a vehicle user I am far from the best infantry player in the match, the simple fact is that I can pick up either of those weapons and do decently with them, the difference between them is that I actually have to try and judge the arc and splash radius with the mass driver, while I simply point the weapon and hold down R1 with the other.

Edit: also who ever said that the AR was OP or "soooooo beastly" in my hands, I simply made an objective comparison of my experience with both weapons. And how is it my crutch if I rarely use it, and why on earth should I care about being relevant in a freaking video game? I state my opinion on matters in the game on the forums and in game to other people, I do this because I want to talk about my experiences in game and how I believe the game could be improved, not out of some desire to be relavent. To be honest the only guy who sounds full of it round here is you.

Depends on the range, at a certain distance you can't rely on the reticule and have to judge it manually, I'm talking mid to long range here, there's also relative heights to take into account as well, those do take some judging, unlike the AR which is point at target, hold trigger, profit, in every single situation, regardless of position, height, or tactical situation.