The machines new or old parked outside shoulda stayed parked on saturday morning at -37c. Nothing good happens at that temperature. Seen a few clubs fighting to fire em up and its just pointless.
Running an overhauled 2011 vs a new 2025 could be a blessing if the 2011 is properly retrofitted. anything tier 2 or tier 3 would be a much better choice.
New diesels with dreaded DEF systems in cold weather is a huge issue in many areas.
I found the Mach Z steering heavy when I switched from my Cat Turbo (non-EPS). I added MPS brackets on my spindles which changes the leverage. It definitely lightens the feel but it also causes you to move the bars farther to achieve the same ski angle for cornering. It saves my shoulders a lot of wear. I don't notice the added bar movement unless I'm trying to move around a parking lot or a really tight trail.
I vote the 600 Etech as well.