I did, and I discovered it was doing something weird with comments, so I disabled it. I should pop it on again and remind myself what that weird thing was.

Edit: Ah yes, it makes all comments invisible.

Edit edit: Oh, it looks like it only does that when it's also enabled with a collapsible comments userscript I also had running. Since that feature is available in yet a third userscript, I disabled that one, and it's all good.

Edit edit edit: Nope, it still hides all comments. Undo.