I had a custom extension made about 2 years ago. Who knew I would start a trend. I had never seen anyone with an extension between the butt and shaft. Mike Webb made mine.
I think the balance rite one would work, but I would be concerned about the weight. A uniloc joint and pin...man that thing must weigh like 2.5 oz.
Mine is made with a plain wood female joint, and a G10 screw. The whole point was to conserve weight. Mine weights a hair over an oz. I LOVE it. At first I had trouble making the transition because my cue felt a lot stiffer without it. However, once I learned how to adjust my stroke and stance to a more correct position, there was no going back. HUGE improvement for me. Really helped me solidify that transition from the B+/A- type play to a solid A. I actually think it improved the hit of my cue. I will not consider anything but a G10 pin from now on. Also, I think, and others who have tried out my cue think, that it actually lowers the deflection by a hair. All around this is just a fantastic idea. I should point out that I am almost 6'3". I personally feel like it would be unnecessary for players under 6' tall. Although on the other hand, it can improve your reach on a lot of shots. The danger is the tendency to let your bridge length grow.
KMRUNOUT