SweetiePie91: Why doesn't a downhill shot "takes away" as much length as an uphill shot "add"??
Yankee Jim's answer is comprehensive (and very, very enlightening). Buried in it is a starting-point formula: one yard for every three feet of elev. I this works for downhills for the middle irons. Wedges maybe one for 4, woods... dunno.
I'm beginning to realise that, given the randomising algorithms, and given the difficulty of dinging shots, note-taking can take you only so far. You need to observe in close detail, you need a detailed understanding of the physics, and you have to trust that the programmers have this too.
Or you just ask YankeeJim.
Of course, just as in real golf, there is ALWAYS a case, even in the most critical of situations, for JHTFT.
"just hit the effing thing"
A bit like life, really. Or, life's a bit like it. (After 9 months of WGT, I'm no longer sure...)