Bit of an update to myself. My dipping toes in water with the cheap device convinced me to try the Pebble Time 2, and man it's an enormous difference in accuracy and real-time feedback. So, if I was going to be spending a significant amount of money on a fitness device I'd definitely recommend the watch. Has a lot more alternate uses too. But ofc if you're looking to stay more in the <$50 range, a ring probably still makes sense.