I had some King/Kong Superscharf hubs a few years back. The front was fine (you can’t really do a front hub wrong!), but the rear had a carbon axle and was non user-serviceable, which wasn’t advertised when I bought it, not particularly Tune’s fault admittedly.
The bearings went after about 6 months, kept on using it, then the freehub body disintegrated (totally), had to disassemble the wheel, send the hub back, it cost me £90, then happened again about 9 months later.
Enough to put me off them. There’s A LOT of reports of freehub bodies cracking, most people recommend you go for the ti freehub (which is both heavier and more expensive than the alu one). I’d not bother again on the MTB, it’s a shame, as some of their stuff looks good, if that new Highfly hub ever sees the light of day it should be awesome!
Having more luck with my A2Z hubs, which are about 1/3 the price, a similar weight and have proven more reliable! Or DT240s.