the racers seem to like 'em
so they must work pretty well. The big advantage is that you can easily remove them from the boat because they're wireless. They were developed for dingy racers who didn't have a power source to run electronics. This is a very desirable feature for boats left alone in boatyards or trailers or for those with multiple vessels where you can switch to the one you'e racing. I don't see a big advantage if you're a cruiser or going to leave them fixed to the boat.As far as how well they work, consider that you need to understand the geometry of racing for them to benefit you .... but hard-wired, good quality instruments will give you the same info. That said, I think they are pretty cool and I wish I could justify spending the money on them instead of the myriad of more important projects on my list.