Well, I moved my seat back last night (from a nominal KOPS position) after reading this thread. In my case it's to try to mitigate hand numbness; moving it back seemed to put my torso in a more balanced position. Less weight on my hands.

We'll see how it feels on today's ride. Really, my knees have been my primary concern; I've ramped up very steeply this summer and pushed through some knee irritation in the process. My fit tweaks so far have mostly been with that in mind.

Will report back what I feel. My seat is now as far back as she'll go. Then again, I'm a very tall lanky fellow.