Some things to keep in mind when reading a "review", also some things to include if you are writing a review.
Snowmobilers tend to suffer from "placebo effect"-- "I spent X amount of dollars, it must be better"
Reviewers area of riding: flat, steep, sea level, 10,000+', dry powder, wet coastal snow, etc
Type of riding, trail vs off trail, trees and drainages, open bowls, chute climbing
Number of miles a reviewer typically does, IN THE MOUNTAINS, OFF Trail
Current mileage on sled and when mod was installed---Currently, there are a LOT of 2020 850s for sale--some stock, some modified with 3-500 miles on them. A LOT of these sleds are not even out of break in mode. Fueling/ Timing is radically different post break in.
Personally, I typically ride 2-2500 miles per year. When home, I can ride right from my property. When the snow sucks here (like it did for a lot of this year) I chase pow all over the intermountain West. I spent over 7 weeks on the road this year primarily in McCall, ID (thanks GreenState) and Wyoming (thanks TRS) putting 1200+ miles on my sled on the road, plus 1000+ miles at home (we are still riding here). The reason I bring this up is that problems/ experiences I encounter with my sleds are diffferent from the guy who might ride 300-500 miles per season and get a new sled every year.
There are a ton of great products in the snowmobile industry, and there is a lot of untested JUNK that is brought to market. I have seen glowing reviews about products from certain members over the years and followed their builds. Then I see those same sleds up for sale and the posted mileage on the sled is sub-500 miles.... doh!
So reviewers, add as much pertinent information that you can in your review.
Review readers-- try and take the reviewers experience in the context of where they ride/ what they ride/ what style of riding they do