>Would there be a repeatable and measurable difference in the amount of output from someone who is bursty productive than from someone who is consistently productive?
Nope. Never. Sounds like a CTO/CIO's pipe-dream.
It's a personal thing that likely has little correlation with overall productivity, and most programmers are bursty.
If you want to help programmers be productive, make them happy and give them the working environment they crave. Whatever that may be.
>Have you started doing anything different or made any changes to your working style that have led you to become more consistently productive?
The only change I've made recently that I'm convinced made a sustainable uptick in my productivity personally (not applicable to everyone) is that I've started following Seinfeld's and many other writers advice.
I just make certain I write code everyday and if I'm stuck I force myself to start sketching out boilerplate/rough-ideas until I get unstuck.