I found the exact opposite and I'd never ever go back to 15's. I picked up close to a mile an hour at the backend which is so important with today's equipment. Carry is as good or better average is up after the change.
Scott, I'm glad it worked out well for you.
The fact that you picked up close to a mile per hour to get to a more effective speed says you could no longer throw 15# equipment at the most optimum level. Unless I'm reading you wrong, in your case it's not really an apples-to-apples comparison.
In the 15# vs 14# debate, the question should really be that if you can throw both weights without
any compromise (speed, rotation, physical endurance), which is more effective? I believe for most (what's generally true), is that 15# is the correct answer.
For anyone, if throwing 15/16# equipment has to be done with compromise, it's not even a question. You go down to 14# balls. Health and comfort trumps everything.