If not for the $560 price tag for the MSD replacment to GM's Opti-Spark -- and the fact that the MSD unit only has a 30 day warranty vs a 1 year warranty from the dealer for the GM Opti-Spark -- I might be tempted to try the MSD unit. I really feel like I need the much longer warranty, though, especially given the price I'll be paying to have this fixed.

Thanks for the info and opinions, though.