Does anyone have any experience of Openrail and V-bearings?

How would they compare in terms of accuracy vs supported rail or profile?

Seems remarkably cheap, even with all the little extras included. I'm normally incredibly wary of any solution that comes in significantly cheaper than the alternatives, but everyonce in a while, I am pleasantly suprised.

Many thanks in advance for any replies.

P.s. if you've never used it but have an opinion, please still speak up.