Took the ELEMNT for it's first proper ride today...
Couple of observations:
1) The setup is really easy and all done via the phone app.
2) You can store multiple sensors and rename them for ease of use, no bike profiles as it stands to reason you can only ride one at a time.
3) The screen is really sharp and contrasty, very easy to read in sunlight.
4) The LED's are quite cool. I've got the left hand ones set to HR zones and the top for notifications and GPS directions...it works really well.
5) I've asked if they can use the left hand LED's for FTP power (indicate above and below FTP) for TT's...apparently this is already in the works and is a killer feature for me. The ability to see if you are above or below pacing with a 1s glance will be awesome.
6) Not tried the Nav yet, but the unit does sync all my Strava routes instantly and the map with breadcrumbs is very clear.
7) I've found the Garmin branded mounts from my old 800 WILL work, as some of them have screws to hold in the replaceable quarter turn bit, you just unscrew turn it 90 degrees and re-screw.
8) I have 4 data screens set currently, but you can program more and there are over 100 metrics to choose from...all from the phone app.
9) It uploads data as a FIT file (garmin format) so can be used with multiple 3rd party sites and tools. If you want to browse the device filesystem, you need to download a desktop Android file transfer app, it doesn't mount as direct storage.
10) Cannot comment on battery life yet, but I estimate from today's ride I'll get about 12hrs. Wahoo have said further code optimizations will increase this as they find bugs.
So far I'm pretty happy with it. It seems to tick all my boxes so far and as a bonus I can use it to control my kickr when warming up for races (power the kickr off a 12v car feed). I'll still keep my old Garmin 800, but strictly as a unit for CX races where I don't care if it gets trashed.