The 310 is ace, comes with me everywhere. No problems in 18 months of using it in multiple countries for open water swimming, biking (all sorts), running and skiing.
Mine is paired to speed/cadence sensors on all my bikes, and older style HRM (with fabric strap) and will work with a power meter if I ever get round to buying one…
Probably a bit slow to acquire the network compared to newer devices, but you work round that easily with the usual pre ride/run faffing.
Only thing it misses is pace alarms in the running section – has HR, calorie, etc, but it wouldn’t stop me buying it again. There isn’t enough in the 910 to make me move to that product.
Very good pricing on it now across several sites.