I used to run with OHR and it was really ok for regular flat runs. The OHR struggled to get a good reading when going downhill fast when there were lots of erratic hand movement in difficult trail runs.
So I went with H10 and I’m happy. For regular runs I don’t see that much of a difference (well, maybe first 10 minutes are sometimes weird with OHR) but when doing trails HR belt is pretty awesome. The reaction time with HR belt is amazing compared to OHR.
However, for hiking and regular walks OHR in S5 works well. I very seldomly get weird readings for no more than fifteen seconds.