My Athlon Velocity Pro arrived on Friday and I had opportunity to take it out to an ELR class Manners hosted. I took my LabRadar LX (which I haven't used much since Oct when I got it), and my Garmin, which I've used a bunch for the last year and a half as my primary chrono.
Athlon had put another Velocity Pro on a "prize table" for the students of the class, and the guy who won it in the drawing let me put it side by side with my unit, as well as another shooter's Garmin, so we had 5 chrony's lined up for a few shooters (at least when one of the Garmins wasn't knocked over by brake blast).
The two Athlons measured within 1-2fps of each other for each shot. The two Garmins measured within 1fps of each other for each shot. The LabRadar LX was ~3-4fps slower than the Garmin regularly, which is well within the specified precision of these units.
The two Athlons, however, read ~20fps faster than the other 3 units. Shooting out to 1860yrds during this class, naturally we were able to decipher which speeds were correct.
I spoke with Athlon yesterday about this, and they mentioned that a hard reset of the unit should correct the firmware and bring that back in line with the other units. So I'm going out hopefully on Thursday to shoot again before resetting, along side the Garmin and LabRadar again, then do the hard reset and see if 1) the offset remains before the reset as I saw it on Saturday and Sunday, and then 2) the offset returns after the hard reset. I WILL report back to see if this reset does correct the offset.
Something kind of neat - I've had opportunities like this where I have carried my Garmin like a GoPro and walked behind prone shooters on a firing line - standing behind their feet, WAY behind the specified placement recommendation - and I have been able to pick up shots without fail. I tried this with the Athlon this weekend as well, and sure enough, it picked up the shots from standing behind the shooters also (with the same ~20fps offset).