Hello David
I bought the 235 about 4 months ago to replace my 220, partly because of the integrated heart rate measurement (on the wrist). I was a bit unsure at the beginning and was actually convinced that I would wear the chest strap during running training anyway. However, it quickly turned out that the heart rate measurement on the wrist is really very accurate. It may react a little more slowly to rapid changes in heart rate (e.g. during intervals) than the measurement with the chest strap, but this is negligible. So now I don't wear a chest strap during running training, only during training or races with the cross-bike.
However, a prerequisite for accurate measurement is that you don't put the wristband on too loosely.

I hope I was able to help you with this. Best regards Chris