Triple-checked everything last night.
Polarity switchs on the mic were correct.
Swapped L/R and tried to decode - sounded like ass, I was right the first time.
Tried inverting polarity on the Side channel, just in case - same problem, but reversed.
The answer. . . best I can tell, being set up a few feet off center is what is accounting for the unequality. Also having a good size crowd on one side and nothing but a brick wall on the other could have played into it as well.
Used the built-in M/S decoder in Logic Express 8, tweaked the direction control until things sounded about right. The wave still looks weird but as long as it sounds good, I don't care what things look like. Sounds real nice through speakers, still a little weird through headphones, but I'm content and I'm done.
-jay