After a couple of years of procrastination, I finally purchased a Fiberbow 6.9 and put it together with my HEX 6.6 limbs. No problems with the fit in the limb pockets, although I did need to move the limb alignment plates near the limits of their adjustment in order to fully align the limbs, string, riser, and stabilizer. It seems that the riser is not quite straight, but not twisted, and everything was aligned to my satisfaction in the end. The low mass of the set-up did precisely what I wanted it to do, which was to relieve the stress on my bow side elbow and shoulder, so I'm happy with that. As expected, compared to my higher-mass GMX, the sight ring wanders a bit more on the target, but I think this will correct itself as I get accustomed to the lower mass. I may add some additional mass to the ends of my stabilizers at a later date to see if I can get the wandering to settle down more. Although I'm waiting to the weather to get nicer before I shoot outdoor distance, the set-up seems to shoot very nicely indoors. The arrows pretty much go where I send them. The reaction is much more lively in my hand than with my GMX, but that is a good thing for me. There is considerably less vibration than with my GMX, but I've also got quite a bit of rubber on the limbs and stabilizers. Overall, I'm very pleased with the way everything fits, shoots, and feels. My only complaint would be with the grip on the Fiberbow. For my hand, the grip is horrible. I can't seem to get my hand settled properly, and the grip slides around during the draw. I've ordered a 2.0 grip from Jager Archery, which is what I have on my GMX, and hopefully this will solve the problem.