You're comparing apples and oranges in my opinion, your intended use will determine what's best for that gun.
I have both, and own/have shot numerous others.
The PRO is hands down the answer for a hard use, duty, apocalypse type optic.
The MRO is more of a range, speed, fun type optic.
The PRO is physically large and weighs like 2.5x as much, more of a tube when looking down it but not bad, maybe a tad sharper dot, lens caps are handy, probably has a few more settings, limited on mount options, holding it you can tell she's ready to be run over with a car then picked up with likely very little poi change (not sure it's actually that tough, but it's a tank). Mine went several feet under water for about a half hour once, I can speak to its water proofness.
The MRO is very open when looking through it, its short and belled out to make vision closer to seamless around the body of the unit, adjustment knob on top so the sides can stay slimmer meaning less field of view loss, it's compact and light, plenty of mount options, mine lives in a scalar works mount that I'm fond of. Caps would be nice but not totally necessary if it's not going to live an overly rough life, battery life is still plenty good, not a perfect clear picture but nothing like my rmr with it's blurred glass and blueish tint. The MRO lives on a vector or a 22lr ar15 where speed on steel is the goal.
Aimpoint t2 may be a good compromise between the two but more monies. I'm not a fan of eotech, wouldn't mind putting more rounds through the vortex uh-1, seemed like a viable option with a short look at it.
I think your use will determine which to get, the real answer is both.