Ok, but consider no auto-save, i'd predict several angry users posting when they lose work because the auto-save didn't save work prior to when their browser crashed for whatever reason.
How long does the auto-save take? 1 second, 5, 10?... is it really that big a deal to wait until it's finished?
Word count i'd agree isn't essential. If you use Firefox there are small extensions that can do this for you if you need it.
You could always set the autosave interval high so that it never bothers you (can't remember the JS file that handles this offhand, but the interval is right near the top of the file, it's hard to miss). You could set it to some stupid high amount, and it'll be as if it's never there.