I have the Garmin and used the Labradar since they first came out - have since sold it.
My first impression of the Garmin is excellent. Compared to all other chronys it is smaller, lighter, quicker (to acquire velocities), and the automatic phone interface is flawless. The old Labradar sat in a Pelican case, so it was a big separate piece of luggage.
The downside of the Garmin is needing a phone and the phone app (Shotview) to transfer shooting sessions to a computer. Currently they sit in the radar's memory as FIT files, totally useless without decoding software. Labradar stored data as CSV files and no reason why Garmin couldn't do the same.
Upside
Some German guy on Youtude did an experiment to find out how far the Garmin can be from the gun before it stops acquiring., and how wide is the emitter cone. You can sit the device up to a metre to the side of the barrel. The emitter cone is 52degrees which means it's super forgiving for aiming. Plus it's also forgiving of structure down range, which Labradar didn't like.
Power draw is excellent. Have had the thing on for 2 hours sessions and dropped only 20% from full power.
Downside.
There's no inbuilt software to convert shooting data to CSV files. This, so when you plug it into a computer you can download usable files for Excel. Currently the sessions are stored as FIT files. That means when you plug the Garmin into a computer all you can do is charge the device, and upgrade software. If you want usable CSV files you have to have the phone app and a phone - pair it - and email the files to your computer.
Someone on the 6.5Grendel forum has written an open source code to convert Fit to CSV for PC's. Doesn't sound like it's fully debugged yet.
Another downside is you can't add bullet weights after you start shooting. Entering bullet weights prior to the start will add muzzle energy and Power Factors to your velocities.
As for the rifle mounts like Area 419, you don't really need to slave it to the gun. Plus the recoil will hammer it. The mounts seem like a solution looking for a problem. The supplied tripod and generous 52degree acquisition cone works for me.