I have been noticeable slow downs and occasional crashes with the headband lately. I believe the new version of ios -- 11.1.2 -- is responsible, but I can't be sure. The headband also loses connection occasionnaly which never happened before. The app also crashes upon opening once in a while.
The animation of the circle during the calibration phase at the beginning of a session is jerky. The countdown during the session appears to run unevenly.
The pause button is unresponsive or takes many tries to work.
My headband is a 2F51
It seems to work fine with Muse Monitor (including OSC transmission). I have used it extensively.
I had put the headband aside for a while (a couple months). It worked fine when I started using again a couple weeks ago. The only change appears to be that ios update.