I used to bowl with my thumb and had a rev rate at about 225. I tried 14 and 15 pounds. I didn't notice a difference in carry.
Last year I totally changed how I bowl to 1 hand, no thumb. In order to learn how to do this which put much additional stress on my hand and elbow I went all the way down to 10. With my about 380 no thumb rev rate I have used reactive balls from 11 - 14 pounds. A few shots with 15 but will not do that b/c I don't want to injure myself.
The points is, I'm not guessing. I have bowled a lot with 12 pound cyclone, 13 pounds BTU pearl, and 14 pounds, mostly urethane.
The big difference in carry I have seen is from 12 to 13 pounds.
There is actually a video on youtube about weight where this is broken down. A small increase in speed makes up for the additional weight, so if dropping weight increases speed a tiny bit, there is no point.
The other factor I found is angle. With 12 pound cyclone if I play the outside, people won't be able to tell it is 12 pounds. If the lanes are breaking down and need to play big inside angle, then the 12 pounds starts to show.
13 pounds hits almost like 14, and that's like 15 as far as I can tell. The biggest factors in power is rolling the ball well and getting the ball to the pocket in the correct phase of ball motion.
All factors being equal - yeah, I guess a 15 would be better than 14. But if someone only rolls a 15 pound ball 99% as well as 14, I'd go with 14. I would say the same as 13 to 14.
I'd go with the weight that feels better and allows you to execute your shots the best. I've left too many 9 pins with my 14 pound Fever Pitch to feel I ever need 15 pounds.
