What features will the Garmin HRM Pro Plus strap bring that I don't already have?

- for running: Ground Contact Balance (% left foot / % right foot) running dynamic, which is unavailable from the wrist

- dynamic HR source switching, which some would say is an anti-feature: it dynamically switches to the wrist HR when the watch deems that the data from the strap is somehow unreliable. [This is distinct from the normal feature which switches to wrist HR if there's a literal signal drop out and/or you stop wearing the strap.] Users, including myself, have found that this feature tends to actually prefer bad wrist HR over good chest strap data, in some cases. Note that this feature can still be turned on with an unsupported / non-Garmin strap [like your Wahoo Tickr]: in this case, at all it does is cause both the external HR and wrist HR to logged to the FIT file [as well as the standard activity HR], but afaik, it will not actually perform any dynamic switching

- maybe better support for HRV than your old Wahoo Tickr, which might be useful if you want to use the health snapshot feature with a strap or you want to use a phone app to measure your HRV via strap

Things which probably don't apply to you but are worth noting anyway:

- the strap can be optionally used as a source for speed and/or distance (just like a footpod), although it will refuse to do so if a footpod is also connected. This probably points to the fact that Garmin thinks a footpod is a better source for those metrics but idk

- Garmin watches support treadmill calibration when the strap used as a speed/distance source, unlike footpods

- if you wear the strap while not wearing the watch, it will collect "activity tracking data" like all-day HR, calories, intensity minutes, and steps, to be synced to Connect, then back to your watch via physio trueup. You can actually take advantage of this feature to wear the strap but not the watch during a timed team sports activity like basketball - in this case, steps would normally not be counted (as Garmin won't use the footpod as a source for steps). But when you wear the HRM-PRO/PRO+ but not the watch, steps will be counted and synced to Connect, then back to your watch, even if you were recording an activity at the time and even if the strap was connected to the watch during the activity

- the strap will also store HR data during an activity when the watch is not worn - after the activity, the watch will prompt you to download the data from the strap. This is usually meant for swimming but could also apply to team sports like basketball. The annoying thing is that it will *also* do this if you wear the strap but not the watch during an activity, *and* the strap is connected to the watch during the activity [meaning the watch already records HR directly]. The problem here is if you accidentally allow the watch to download the HR data and merge it with your activity, it can actually corrupt your activity HR data. So this is kind of a pain in the "team sports" use case, because you have to remember to cancel the process of downloading external HR data after the activity

Also, if you're curious about HRM600:

- this adds step speed loss (with a compatible watch like FR970)

- this adds the ability to record a timed activity from the strap itself (no watch necessary). The process is kicked off by pressing a button in the Connect phone app, but the strap doesn't need to stay connected to the phone afterwards