Curt, thanks for posting the vertical rafter depth table, that is a huge time saver. The biggest beef I have with CA when it comes to designing roofs is that once you set a roof at a certain pitch, the baseline is placed in a position that if you change your roof to a different pitch, the roof is then in the wrong place. I end up deleting the old roof, changing the pitch, then re-drawing the roof rather than trying to figure out the new appropriate height based on the changed VRD value to keep the heel height consistent. Not sure if I'm explaining this well... In any case, if you draw a 12:12 roof with a 6" heel height at the correct location and then want to change it to a 6:12 pitch, the heel height will not be correct.
This seems like another case where the software is driving the construction, rather than the other way around. I think there should be a heel height entry option on a roof that would allow you to define the height of the heel from the top plate to the top of the top chord without having to determine the VRD independently.