I've put 3,500 miles since my rain sensor module was replaced. I went from multiple courtesy wipes a week, sometimes 10 in a row to zero. It has been flawless with one exception, it did one wipe once in that time frame and I'll chalk it up to moisture on the windshield.
No sensitivity change.. it's been a nice fix!!
My dealer didn't duplicate it the first time but after showing the video I took from my cell phone showing the 10 wipes on a bright sunny day, they said they'd contact Ford and a few hours later, a module was on order.