RE: voltage regulator ?
Will it? Yes. It's been proven. The test was conducted between a 4 cell and 5 cell pack which is a much higher difference, and the actual consumption was increased by around 5 percent. In other words, a non-issue.
The practical answer is, the difference in performance on that plane, and the difference in consumption, would be so negligable as not to be noticed.
Pick one and go with it.