Yes I have. I've used both the MIP non-HD shafts and broke one within the first 3 minutes of putting my truck on the track. MIP came out with a second design which is much more aggressive, but it's still a telescoping shaft.
I then went and bought the Tekno's. I broke one, but it was IMMEDIATELY replaced by Tekno as soon as I notified them of the break. Since then, they've redesigned the shaft, so the newest ones will be more HD than what I have now. Since my first break, it hasn't broken since, and my truck has been to 3 different tracks, Revelation which is a big 1/8th scale track, Pegasus Hobbies, and LRH. I've put at least 10, 2s 5000 Lipo packs through them at this point.
My setup is a Castle Mamba Max Pro with a Novak 4.5 Ballistic HV, geared 14/54.