I love my 500, being a heavier guy at about 265lbs right now (I'm not a total fat ***, I was a college football player as a lineman I'm 240 when I'm skinny with zero shame in my game with my shirt off) and I can't imagine being on anything else. I ride with a buddy on a KTM bored out or whatever to a 6 oh something on a Yeti 137 and my 500 with a TS 137under load still eats it. On the trail my bike sucks, no 5th gear and I don't feel like twisting it to the locks the whole time so I cruise and it's not all that fast his bike is better on trails, lake beds it's a toss up, if his bike has the power to pull 6th because of snow...he wins. If his bike can't pull 6th because it's deep the 500 runs on it.
My bike on maintenance is pretty much drop the quart of tractor hydraulic out of the case when finished, add a quart when ready. Its not that sensitive to jetting..our conditions are usually pretty similar week to week, storm to storm. We go from around 7000 to just under 12ish..it handles it well, especially because you are wide open often. I'm on my second year with this top end, just had the reed block out and the piston and bore look great. 500's crack the skirt on the intake side if it's going to go, mine doesn't even show wear yet...I'm going another year on it at least. Rebuilds are about $250 with machine work and gaskets and anyone that can put together IKEA furniture can easily handle the job. I really don't mess with jetting that much...I deal with the maintenance on the track more than the bike. I have ridden my buddies KTM, it's O.K. but it doesn't explode like my 500 when you need it to get some...my bike pulls 3rd easy on most climbs...It has decent torque for putting around in really tight trees too...for me it's perfect.
I think the 4 stroke is maybe easier to ride, the gear stacking and area of usable power is wider, the 2 stroke takes more rowing through the gears if you want it to be sitting in the meat of the power but the power explodes and the thing pulls hard.
I ride 500's for everything. I have an AF for singletracking and another just for sand. The things can be beat on flat ground, it's tough to sometimes get the power to the ground and you have to hit your shifts just right, my buddies always want to drag race me and when they win you would think they were the quarterback on the winning superbowl team. If you put the bikes under a heavy load like a sand dune, deep wash, snow...it's not a contest.
All my friends ride KTM's or Husky's. most have multiple bikes for different situations. All have their HP claims. I always get crap for my Dinosaurs, I always dish the crap back by saying those Austrians measure HP with little mini horses. Ride what works for you.
As said before, you being a bigger guy I do not think you will be happy with a 300.
The supercross 2 stroke argument is silly, that move was all politics.
The 2 strokes don't belong on snow makes perfect sense though, if two strokes were any good in the snow you would think they would make a 2 stroke snowmobile that was fuel injected and made great power to weight...and it seems 4 strokes rule the snowmobile world.