Originally Posted by Puget Pounder

Very true with one caveat. For smaller riders where the range of fit is not as great as normal-sized riders, angles become increasingly important. a 1 degree angle change can be a drastic change and can be the deciding factor between a stem size in the acceptable range or "twitchy". Knowing angles and lengths makes predicting how the bike will handle for a long ride instead of a 5 minute test ride much more predictable.