Distinguishing trivial and non-trivial merge commits

I'm trying to get a goot notification script, and got stuck with merge commits. My script shows a list of modifications for each commit (based on the diffstat output) -- and if I show all commits, then merges are misleading in that a quick glance through the email makes it look like a lot more was touched. Using `--no-merges' helps in avoiding the confusing parts, but that's dangerous in omitting non-trivial merges too -- and those are probably even more worth noting than other changes (just because they'll highlights changes that are "hotter" in the sense of more people working on that code).

The only way I've seen to distinguish the two is to use `git show' and see if there is no diff output (eg, "git show --pretty=format: $rev"). But that doesn't help in getting the list of modified files. So I add `--stat' to that, and that goes back to showing all files again, the same stuff that "git diff $rev^!" shows.

Is there *any* way to get `git diff --stat' to do the same thing that `git show' does? (Or a way to get `git show --stat' not show all files again...)