The newest carbon version rev B upright SP makes have a thicker section where they used to break. I've had no issues with those and I run on a board track.
http://shop.speedpowerrc.com/steerin...nforced-rev-b/
I had binding but with constant adjusting, every race day, of the insert that screws against the upper pivot ball no more issues. I also had some binding with the stock bellcrank but I switched to the alum bellcrank bridge piece and that make a huge smoothness difference. Also the lower POM pivot ball helps smoothness
At my local track the Sp is the current king against new VBC and all the Tamiya