Yes, it does work. But it could be better. We have used 1/8 rod, preferably brass. It adds about 29 gpi. But, the drill that came with the kit is too short....you can only drill less than a couple of inches deep. I bought a 12" drill bit in 9/64" and experimented with deeper holes. Finally settled on about 3" depth as the most I can control.
The problem, in my opinion, is it is a great idea that suffers from sloppy tolerances. The hole in the jig is too large and the "guide bushing portion of the jig is too short-only about an inch. So the bit can wander in an arc, and the varitions in grain help it wander. If you are not extremely careful you will drill out the side of the shaft- even with a 3" depth. However, we also found that you can stop the instant you see that happening, and it doesn't cause a big problem. You don't want an air gap under the rod anyway(as it will weaken the shaft greatly at that point), and the tiny hole in the side is left filled with epoxy. With proper care when drilling, I have that happen with about one shaft in a dozen. I only use those for practice or stumping, but the surprising thing is there is no apparent difference between how those shafts shoot, compared to the others. (maybe that's a clue to how well I shoot, huh?)
Some observations based on several hundred shafts so far:
The misalignment of hole or rod seems to mean very little. I think the difference is that it is close to the centerline of the shaft, and the same amount of eccentricity or unbalance might be much worse if it were on the outside of the shaft surface.
The shaft is strengthened only if the hole is filled to the bottom with epoxy and the weakest point of the shaft is moved to right behind the reinforcement. It is tougher than before, but if you hit something hard enough, that's where it will break.
We've had shafts which hit something hard, and the cedar/rod actually bent behind the point, but didn't break. I was actually able to straighten a couple of those, just as with aluminum, and shot them again. Once again, little apparent loss of accuracy(!), but you'd have to think the wood could have been weakened at that point. Not advising using such shafts, just curious if they could be straightened.
It would cost too much, but if I can ever find a machinist who would do me a favor, I'd have him make the same thing except to make the guide bushing(the part with the small hole)smaller in diameter and longer. It would then allow less slop when drilling and the process would be much more accurate. Then you could drill deeper and get more FOC and I'm sure, better accuracy.
Once again, it's a good idea. I like the idea better than woody weights.