by coincidence i'm looking at the EPSON RUNSENSE PS-810...might be just what you need. Great bit of hardware...the software around it maybe less so. In fact I did some tests of my garmin vs the Epson a couple of hours ago!! not yet got to analyse them . the epson's hr seemed generally good even up to 170bpm. but as I say will have to look at the results.
It looks reasonably likely that there will be a 630 either this year or early next judging by the historical release rates of the past for Garmin.
Does anyone have any views about what might or should be included in the Garmin Forerunner 630? Share them below if you do. I struggled to think of THAT much to add to the 620. ie new running FEATURES rather than bug fixes or bits of tinkering about.