I'm not sure how I failed to find this during my great miter saw hunt a few weeks ago, but back in 2002, someone named Tom Judkins penned an awesome post to rec.woodworking that goes into how to decide on a particular type of miter saw. His level of detail is terrific, and he includes a lot of tips on how to check whether a saw will cut true, kick your work off of the table, and help prevent injuries. It's worth a bookmark in any woodworker's browser.