I previously had an Ionic that was unfortunately recalled. I loved it because I could make up whatever run workout I wanted and see the performance by individual segments just by clicking a button on the side of my watch. The Sense seems incredibly limited and requires breaking up my runs into 3 (or more "runs") to get that logged in a useful way by Fitbit and Strava.
For example, I almost always do a warm-up/cool down portion of a run, along with either tempo, interval repeats, or fartleks in-between. With my Ionic, I simply pushed a button to indicate the start/stop of a new interval and I could see my performance for each section after. There is no good option to record these sections differently with the Sense. Even the interval option is horrendously limited, ie no warm-up/cool-down without breaking it into a separate run, and as far as I can tell, it's impossible to do any kind of distance based intervals.
I know I saw someone else complain on a separate thread on this topic, but really surprised (and discouraged) that this feature wasn't replicated from the Ionic.
