Re user counts; we have, I think, 1 editor who has 1M+ edits. I imagine we don't have many with 100K edits. How big are those user groups? It's useful to know that power users are more likely to opt out, great, but if you only have 30 users in your definition of 'power users' it's going to be thrown off very easily.
My big worry would be that finding this out only tells you that either (1) only power users have a problem or (2) only power users can find the off-switch. Comparing with other features that also feature an off-switch would allow you to eliminate this as an independent variable.