I really like the timing facility, but I have little clue about my pace over flat/up/down sections. (I know the presets are probably the "average" person, but I'm sure variability is huge.)
It would awesome to be able to upload a GPX file that I recorded that corresponds to a defined route. This data would be used to estimate or "fit" the various timing parameters (flat speed and uphill & downhill distance increases per foot elevation).
The idea is that these parameters would apply more closely than the average-based preset on various other routes.