I've been using a Pact XP (originally a Model 1) since 1991. It's been, at times, a love/hate relationship. When it's working correctly, it is fantastic and very consistent. However, where I am now is out in the woods - literally! - and the sun angle can be critical. Too low and the trees block it and it won't work. Cloudy days actually work the best! If it registers, the data is usually good, although every once in a while it'll go nutzo & give me a reading that I know is way off... like 2700 for a .22 LR! That's usually an indicator that the sun it getting too low. I upgraded to the IR unit several years ago, which should work in the dark, however, I've not had good luck using it. I suspect that the angle of the IR reflectors has to be "just so" for it to work.
I wouldn't mind the MS but I have too many firearms it won't work with, smaller pistols and such, so the alternative is the LabRadar. I'd like to try one out but since my shooting lane has trees on either side, it could be problematic. Plus the cost... whew!
I guess I'll stick with my Pact until I'm forced to go another way!
Cheers,
crkckr