That HR strap works with your SRM PCV beacuse it is ANT (no + after it). But it will not work with the Garmin beacuse it is not ANT+. They use two different protocols.
I don’t think the SRM PCV is compatiable with an ANT+ strap. The newer PC’s are, but as I recall the PCV is not.
In short, I think you are SOL if you want HR and SRM PCV Power on the bike and use your 310XT with HR on the run.
The Suunto dual strap is not immune to static problems. I have the first version of the newer strap from Suunto (comfort belt) before they added the interface with gym equipment (dual strap). It is the same construction, but does not send a signal to treadmills, etc. This Suunto strap worked well for nearly a year, but then developed issues where the signal was dropped. It is much less reliable than the older Suunto straps. I do not know how it compares to any of the Garmin or Polar straps. Maybe the lifespan of the strap is only 12 months.