Got heart rate data! Will give further info when at desktop
After having considered FR 235 and Tomtom spark I opted for standalone optical monitor that paired with my FR220 with no issue. This will give me future flexibility when I replace the 220 and not be tied to integrated optical monitors where they work least well.
Got this oneMy plan is to wear it on upper arm either side of bicep. Didn't have time to get comfortable fit so wore it on fleshy part of lower arm.
Locked onto cadence for first 10 minutes or so, then was grand until last downhill section which was more vigorous running and locked onto cadence again. The first 10 mins was not surprising as it is an issue with optical monitors in cold weather but disappointing that it fell out near end, but this happens in the likes of interval sessions.
I'll try for a comfortable fit on upper arm and see if its more reliable in that position in cold weather.
FR220 does have heart zone feature, may use that in future.
Tried chest monitor and it wasn't for me.