I know this thread is from last year, but let me give some personal experience advice about buying one of these "boutique doppler radar chronographs"........
DON'T DO IT!!!
Just buy the damn Garmin and be done with it. I spent $1,200 (with tax) on a Bulletseeker Mach4 that sits in its case collecting dust, because it's picky and finicky and only picks up about 6/10 shots suppressed, and the owner of the company WILL NOT contact me back about getting it replaced with one of their new upgraded units.
That said, the app is nicer than the Garmin, and it allows you to stop and continue, and switch between the different shot strings at the touch of a button, which is REALLY nice. I wish Garmin would implement this in their app. But other than that ONE feature, the Garmin is superior in EVERY way, and costs half as much. It picks up 9.9/10 shots. I've only had it miss maybe 2-3 (out of probably 1,500 shots now), and that was because I either shot too rapidly for it to register, or something caused it to glitch...