Can you change a Matthews grip out to something slimmer, or do you just deal with it?

Just pop it off and put you a new one on.

I shot their bows for 14 yrs. and never found the grips to be a problem. I know a lot of people who dislike them though. The last one I owned was an Apex 7 which has the integral grip. It was by far and away my favorite out of all of the Mathews bows that I have owned. If your looking for an aftermarket grip, Shrewd makes a nice one.