I think the issue is what has already been mentioned. The hype and videos of FX Fanboys using this device show guys just plopping it down under the muzzle of their guns, and shooting away, happy as a clam. Unfortunately, it doesn't work that way. Really, it doesn't...
I've set it six inches back from the muzzle due to table size - doesn't work. I've set it beside the end of the muzzle, less than 2 inches away, and aimed at the same spot as the muzzle - partially works, one shot every now and then. I've set it lower than recommended, because the bipod wasn't high enough to place the device at a height above the table - partially works, one shot every now and then, or a few shots at the correct velocity, then one or two unreasonably low (from a gun I know has an ES of under 10 FPS).
So does it work when its set up EXACTLY as directed? Mostly. I've had to increase the sensitivity from 20% to 10% in order to get consistent readings with high speed .22 caliber 15.9 grain JSB Exact, like 950 FPS. Don't get me wrong, I like the unit. But is it like an Apple computer where you just turn it on and use it mindlessly? Nope... Improvements with the app will make it even better I'm sure, and I'm also sure that FX won't leave us hanging with the unit as it currently is. They have always worked with customers to improve their products.
Yes, I have one of these units. And yes, I have two FX rifles - and have owned two others in the past. But I'm not an FX Fanboy, and like my Eastern European girls better...