Um... whoever said that the SNES version of EWJ lacked the descension level before Buttville were either totally wrong/ nedver played the SNES version/ or are totally ignorant. I know I've played that level on the SNES, in fact at one time I never every single difference between the Genny and SNES versions down to the finest detail. So I'm gonna boil it down.
Graphics: SNES hands down, the Genesis version didn't have the same sun effects in New Junk City, or the transparency effects weren't present in "What the Heck".
Sound: Although the Genesis version does have more sound affects and dialogue, the SNES version was clear and vibrant.
Content: This is where the arguement turns against the SNES version, the Genesis version had the extra level. The SNES version only had a few 'perks'.
I still give it to the SNES version though, Intestinal Distress was actually good level though.