I run them on both my RMK's with no problems. But then again, they only go down when I need them. As far as lasting longer I'm unsure yet, wearing out is a given with anything dragging thru ice and hardpack. Drag it long enough, it'll wear out.
If sheaves/belt is glazed, I use a fine sandpaper to lightly clean and scuff. Follow that with a good soap & water wash, finish with a thorough hot water rinse. Blow out with compressed air as needed.
I've got same sled w/ FasTrax built 825 UBR motor in it. My issue is the reverse of yours. I'm jetted for 7k-10k and use FasTrax PowerJets to fatten it up when riding below my jetting. Works well for my usage.
This will be my third year wearing a Klim version of the Freeride TekVest. Tried and tested many times last season. Won't even consider riding without it. I wear mine under jacket.
I use the shoulder flaps as well, seems more comfortable with them.