No, the Garmin Running Dynamics Pod is not better than Garmin HRM Pro (which is a newer product). Both provide the same running dynamics data. I've had both (and still have HRM Pro+), and when comparing the produced data, HRM Pro(+) actually gives more frequent running dynamics data points, the pod provides dynamics data every two seconds, HRM Pro(+) every second. Not that it probably makes any difference, though...
Theoretically it's possible that the location of the pod (near your hip) is more ideal than that of the strap (chest-level), causing it to bounce slightly less. But on the other hand, the strap is directly connected to your skin, the pod to your clothes, so that might cause the pod to actually bounce more. Who knows?
But based on my experience both gave me ok data, and mostly similar. Vertical oscillation figures were somewhat different (because your torso is somewhat flexible vertically), but that's something Garmin has documented and accounts for in the scale. The reason I switched was that my old HRM strap broke and I replaced it with HRM Pro+, so there was no point in using the pod anymore and I sold it.
