I am using it now. Super light weight... No real wear to see on it after a few thousand miles. It eliminated the cush drive and the weight savings is amazing. Great mod!!!! One of my top!
I've had their hub in my ST4 for 3 years now with zero issues. There's no cush system in it but I don't notice any differences in the drive feel at all. Nice part. Probably more durable than the stock hub. A little lighter too. But to be honest unless there's something wrong with your stock hub I don't see an advantage with using the Vee Two hub except a slight mass reduction, maybe a pound or two at most - and on the clutch a two pound loss isn't all that noticeable. Two pounds off the clutch is equal to about one pound off the flywheel. Barely noticeable.