In other words, I guess I'm trying to figure out how much of the bells and whistles on these watches are just marketing gimmicks and how much they might actually improve my running.
My answer is probably yes. To give more definitive answer, I'd need a time machine and repeat the last 5-6 years of training without s watch. It still be N=1, to have a scientifically accepted answer, we'd need many more time machines :)
Very few data points, generated by modern sport wearables are actually actionable. I find those helped me to get faster:
- GPS for mile alerts. Simply knowing when I'm done with my 5, 10, 15, etc mile run. Without watch I'd probably have to spend a lot of time planning with a map beforehead
- Constant heart rate monitoring for long runs. Recently I don't glimpse at the HR very often and mostly run by feel, but it took years to trust my RPE. I needed a watch to know how hard I'm running for the first several years.
- timing for intervals, both on track and in a pool
- GPS for pacing in races. Of course you run first 3 miles too fast. A watch helps to minimize that.
Can modern smart phone do all this? Probably yes, but a sport watch is better:
- you don't have to think about battery life
- the screen is always on
- there a convenient buttons
- it's simply more convenient to have a light device on your wrist than a heavy smartphone on ... I don't even know, where do you put it if you want to monitor your pace/heart rate?