HRM Dual Running Dynamics Capture

I love my Garmin Forerunner 235 but am now interested in getting the HMR-Dual.  The Forerunner 235 is not compatible for the running dynamics data so it looks like I would only be able to capture heart rate with my watch.  My question is, is there another way to capture the Running Dynamics data with some sort of third party app I could use or should I just get the HRM-Run?  Thanks!