RE: how light is too light.
I forgot to ask what year your Bowtech is? The '05 models have more of a cutout in the riser so the NAP rest might not work well. I used the quicktune 4000 on my Buckmaster G2 and it worked well. It does not work on my Bowtech Defender. If you find that you do not have enough left adjustment and you want to keep the QT on your bow, call NAP and they will send you a new offset piece where the prongs mount. I got one but I had already bought a different rest. If you use it, make sure that your cock vane is pointing down and the cord is adjusted properly.