I have two Garmin devices: a watch and bike computer. Both are connected to the same app that collects data to a single Garmin Connect account.
I expected some synergy but I got nothing. When monitoring the same activity with the two devices you just gets dupes (for example, sum of the distances measured by the two devices). This is worse than if I had 2 devices from 2 different brands.
Right, Garmin doesn't support simultaneous recording on multiple devices. But if you've got a bike computer then there's nothing to be gained by also recording on your watch, you won't get any more data.
There's another related defect if you use one of their chest straps that records and stores heart rate data for later download (this is mainly for swimming activities where radio can't be used). If you record an activity on your watch and it syncs to Garmin Connect before downloading heart rate data, then after the watch downloads from the chest strap it will create a duplicate activity in Garmin Connect instead of updating the existing activity. Customers have been complaining about this for years but Garmin doesn't care.
I expected some synergy but I got nothing. When monitoring the same activity with the two devices you just gets dupes (for example, sum of the distances measured by the two devices). This is worse than if I had 2 devices from 2 different brands.