I got the 830 and have used it for a couple handfuls of rides. In that time, it has been unreliable. Various things it has done at one point or another (or multiple incidents per ride):
Unable to keep a connection to my sensors (Garmin speed, radar, plus Stages Power) and phone (iPhone XS Max)
'Constantly' losing GPS connection (I have it set to GPS + Galileo).
So, I upgraded the firmware to 3.50, then ...
Device locked up during a ride and I had to 'hard reboot' with the device's keys.
To remedy that I reset the device to factory, then upgraded the firmware to 3.50 and re-paired my devices and phone. That seemed OK for a while, but then during a ride yesterday it rebooted.
I got the 830 because I wanted the maps that I do not have on my 520, plus the trail forks integration. If it weren't for the Varia integration I probably would have just gone with a Wahoo.
I'm 'torn' because I've been usually pleased with the Garmin devices and they are mostly reliable. Did I just get a 'crap' sample? I can probably exchange it for a replacement but thought I'd see how you guys were getting along with yours. Otherwise I'll return it for a refund and wait until Wahoo can integrate with the radar and move on.