I bought a Labrador after way too many disappointing day of jacking with the others and then not being able to make sense of any of the numbers. If you can't afford the Labrador, buy it 50/50 with a shooting buddy or save your money until you can afford it. The others are quite literally a waste of time and money. Honestly
Magnetospeed unless you have an actual need for the few features of the labradar that set it apart. Labradar is just more bulk, more expensive, more battery guzzling, with a more terrible user interface. If you don't want to deal with the POI shift, there are adapters you can buy to get the bayo off the muzzle. For me and everyone I know personally who uses one, the POI shift is pretty predictable and does not affect grouping, just moves your POI.
I have a magnetospeed that has been used on just about every different type of barrel contour/brake setup and have never had to do what you suggested.Labradar & Magnetospeed two different technologies. If have the $ go Labradar. The Magnetospeed uses electro-magnetic field interruptions caused by whizzing bullets at set distances to calculate velocity - not light dependent. Getting the thing to stay in place might involve duct tape or buying a rail type attachment.. The rail mount looks like the best way to go for fine accuracy . The rail might involve drilling then screwing the rail onto a fine wood stock but needs a short barrel to work or possibly some extension sticking out from the stock forearm.