I carried mine by the tripod like a go-pro handle behind multiple shooters on Sunday, pointing generally in the direction of the target, I could pick up shooter by shooter, even standing behind them on the firing line. There were several mounted to rifles at the PRS finale in November, and as you might have noted, a lot of folks have started offering rail mounts for the Garmin - a lot of us are carrying rifles with Garmins mounted and picking up our shots on the clock. Admittedly, I bought a cheap arca rail instead of the more expensive GreyOps or Area419 mounts, but it's working just fine. I bought mine with the intention to mount it to my ELR rifle, which is largely static from prone, but after playing with it, I'll likely be mounting it on my rifle for some matches, or at least some stages this season. It could be hugely beneficial to get instant feedback without detrimental consequence to be able to confirm or correct velocity if a barrel is misbehaving.
The downside of WEARING a Xero like a gopro would be the aiming, and obstruction. On a helmet, it might work. On a chest mount, we'd have arms and the gun obstructing the target view, and there's too much opportunity for the unit to not be pointed closely enough to the bullet travel. A helmet/hat mount... Yeah, that could probably work... or maybe an over the shoulder mount (probably not as reliable as the head/helmet/hat mount).