I haven't. I just purchased Yakima tracks, but I still need to install them. I question how much stress the 2-screw mount can take. It might be fine on a tent trailer that is in the wind shadow of the towing vehicle, but a canoe up on top of a camper could put much more pressure on the mounts.
I was wondering about that as well. Sounds like the materials are pretty good but it's the contact points I was concerned with. Yakima or Thule would probably be best. What's the mounting option you went with for the Yakimas?