I got a 2box hihat. Comparing the Yamaha RHH-135 with the 2box, the Yamaha does foot chick / splashes better and is easier to calibrate. Transitioning between levels of opennes seems better with the 2box. I was expecting a bigger improvement. Without having the 2box to compare with, the Yamaha didn't seem completely compatible.
With the Yamaha, you have separate velocity curves for the pedal and the pad. With the 2box, the pedal velocity curve does not affect the splash level, (Edit: it does affect the pedal) which is too loud, and does not trigger well. This is probably due to the pad triggering instead of foot chick, which also explains the weird foot chick sounds I get with the 2box hihat. Maybe this can be solved by lowering the level of the pedal samples when creating the dsnd in the 2box editor.
I find the edges of Yamaha cymbals a bit too soft. The 2box has a harder surface which I personally prefer, but that is actually the only improvement over the Yamaha at this point. (Edit: no hotspot on the 2box hihat, but the Yamaha does)
Unless I manage to improve calibration, I will probably keep my acoustic hihat.
The old ddrum4 hihat is quite superior when it comes to playability, but the sounds are of course limited. Maybe I'll try it via MIDI.