I've had time to get to the range and try out the new SLiX-Shot nipples. My experience is rather middle of the road. One thing that I can say is that absent filling in the groove in the hammer it does not solve the problem of the caps getting sucked off the nipple. I have found it does relieve the problem somewhat though. I fired about 25 shots and had a few cap jams. The nipples do tend to blow the caps apart into a nice cloverleaf pattern (using #10 CCI caps). The nipples are just a touch too long as well so the caps seem to sit a bit higher although they still clear the frame as the cylinder rotates, but not by much. Ignition was very consistent, I never had to hit a cap twice which was an intermittent problem as my reproduction 1860 got fouled a bit with the old nipples.
My only real complaint is that occasionally the SLiX-Shot nipples will throw a piece of hot cap back on my hand. The old nipples did this occasionally as well but with lower frequency. I was shooting on a windy day so that might have something to do with the problem.
Overall I wouldn't say that these nipples are a must buy but if you're in the market for replacement nipples they certainly aren't overpriced or an inferior product.