How many miles do those little wheels last?
I considered them with my RX-1 and Apex, but one guy I know (remotely) who went with them said the bearings didn't last much more than a couple 1000 miles.
The other question I have is do you notice an improvement in performance to run 4 extra wheels (keeping the track better in contact with the snow, etc. or something)?
Previously I've always run the 04 RX-1 idler wheels and I've been getting about 6000 miles out of the wheels and hyfax. This time I'm running 4 Skidoo idler wheels and 2 04 RX-1 wheels. At the current rate, I expect the hyfax to last literally forever. Even riding on a road covered in sandy ice the hyfax doesn't wear down or overheat. I can't imagine anything better than that from a cost/durability point of view (but I can't comment on how much of a performance improvement there might be with a different solution).