I don't know mercurial, and I agree about the limitation you mention for stashing the index. That said if I need to do a refactoring or something else while I have an unclean tree, I stash before doing it, then commit it, and then unstash my work.

> What hg has is a few different features that make it possible to build up not just a single commit but an entire commit sequence and do operations on that commit sequence (like reorder them).

Again, I've never used hg (beyond a simple tutorial), but you can commit frequently with git (every few other changes "WIP") and reorder / fuse / edit later through interactive rebase.