Not specifically on the head speed. But to help answer your question, the -10 has 3000rpm, and according to the calc, my range with a 30C battery is approx. 3116-3506 on the headspeed. I dont typically drop my batteries below 11.4,11.5v. I use a 12tooth pinion on the slant and have tried a 13T as well. Have experimented with curves in normal ranging from 60% up to 100% and also tried govn. mode all ranges. I have seen the vibe occasionally at beginning flight and end of flight at various head speed ranges, but...not every flight however, it is rare if I dont see it. I was concerned about shaft/bearing slop but with the boca ceramic bearings that has been eliminated. Tiny bit of slop in the cyclics, but the align servos had that too. Also the motor shaft had tiny bit of slop and I changed bearings & shaft, no slop. Everything looks concentric throughout the head/flybar, all measured with calipers. Sorry to ramble on, just trying to not leave anything out.