Would they replace or repair cameras due to other defects!
A bit of personal experience with the brands...
Sony NEX-7, out of warranty, had to replace entire shutter assembly. Sony quoted a very reasonable amount plus shipping, and entire turnaround was 15 days.
Fujifilm X-E1, hot pixel cluster on sensor, hot pixels on LCD and one broken Q button out of box. I was in China when I found out the problem, so I had to send the camera in for repair instead of returning it as I should. No charge, Fuji replaced the lcd, fixed button and did pixel remapping. Entire turnaround was an amazing 6 days!
Canon, various repairs out of warranty, lens turnaround is usually longer than a month - I suspect some L lenses must be serviced in Japan. My 7d shutter replacement was quite expensive, but they sent the camera back in under two weeks.
If it takes Leica 8 weeks or more to replace a sensor from a not-so-old body (Isn't the 7d about as old as the M9?), that's much, much slower than the industry norm.