My only experience with MDMA was weird, I just sat around my friends room talking to him all night thinking this wasn't doing anything until I moved the black out curtain away from the window and realized it was mid day. I bet had I had the resources I could have sat quietly in a room full of people and drawn the entire time. It wouldn't surprise me if it was mostly speed. The jaw grinding thing really creeps me out too.
The jaw grinding is an annoying side-effect that can be handled well with some chewing gum. It also depends on the dose and (apparently) how muscular of a person your generally are. I for example don't get jaw problems unless I go for 150mg. At 100mg it is not a problem. Some magnesium beforehand seems to help some people, maybe try that before the next time.