OHR will always be inferior to ECG approach used by chest straps. This is especially obvious with interval training for me. Some OHR are better than others but none will beat an ECG strap.
I received the Rhythm 24 over the weekend and went for a first run with it this morning. Have been using a Rhythm+ for years with several Garmin watches. Connected the Rhythm 24 as a HR monitor and a footpod in Run mode - via BT. I'm not sure how to force an Ant+ connection, but am happy to try.
My HR appeared accurate, but cadence was WAY off (20 avg vs normal 160 avg). Likewise, stride was way off (I know I don't have an 8.22 meter stride) and Training Effect was practically zero when it should have been 3.0+. It looks like there are some issues with Garmin devices that Scosche needs to work out. My observations are consistent with comments over at DC Rainmaker
Out of interest are these infinitely better than a Garmin optical?
Reason for asking is that I see the benefit when the only option is a strap, but why would you wear one with a Garmin with OHR.