What does your off trail look like? Lots of tight trees? open mountain areas?
I have a 2017 sidewinder MTX so I will answer your 4 stroke off trail question with my experience.
If the current sled you are on does good for you and you can manage in the trees you will love a sidewinder much more especially if your current sled isn't turbo'd. You get to steer with your throttle and while you notice the weight at lower speeds but if you do some route planning as you go it really isn't that bad. I ride trees here in AK and mine does fine as long as I pick more conservative lines but my buddy who lives his life riding can hop on my sled and go up just as much insane lines as on his Polaris so it is really just rider experience.
If you are more primarily off trail I would look for a 2020 Sidewinder BTX as those have a longer track and larger paddle but will still handle ok on the trail, my MTX is a pig on trails (as you could imagine) and I can't go faster than 60ish mph without tossing lugs off the track on hardpack.
Honestly it is sad to see the amount of people on here just saying 2 stroke. The 2 strokes, especially Polaris, do ride a lot better in the tighter trees as they are more flickable but feel underpowered (in comparison) when you get out into the open to ride.
Getting stuck is awful on most sleds and although it does feel a bit more nose heavy when stuck it isn't bad. The golden method for me is to make sure you get the track out of the trench and really stomp the front down (most important) as the intercooler turns into a bit of a plow, then a solid ski pull will get you out, maybe with a ghost ride or not depending on the snow consistency.
