I've ran the Z bros Kit on my 2019 850 then transferred it over to my 2021 850 T. Its been good, to be honest can compare back to stock cause its been so long since I have rode a stock suspension. Purchased my kit from MB Suspension. They have been great. Blew the shock apart in year 2. now have 3 years on it, will be selling the kit with this sled this time....
if you like Tmotion I would go with the Tom's set up. I also like Tmotion and this set up makes it how it should perform, less resistance in the skid to tilt, more predictable, overall I love the set up. I don't think it reduces a lot of snow, just a bit and easier to remove snow. Had it for 2 years on a turbo 19 165.
Really happy with my exit kit so far. I went with the x2 aggressive, and it works great for me so far. I was launching off some lips last weekend on my first ride out, and I didn't think I was getting off the ground until I looked back and saw the 20+ft gaps in my track. So smooth on the landings. The trail performance is also really impressive.
I can't comment too much yet on deep snow performance. I need a couple more rides on it to make any comment. It does seem to make the t-motion a lot more responsive though.