As my search for a Leica M film camera continues, here's a question for those with plenty of experience with older bodies: Just how old can one go and still retain a decent level of reliability? In my case, I'm looking at M6's and M5's. One can get a lot more bang for the buck with an M5. But those cameras are more than 40 years old. M6's are generally 15-25 years old. Yes, I've heard plenty over the years about how great all-mechanical Leicas are and how they can always be repaired. But a 40+ year-old camera is still a 40+ year-old camera. We hear about expensive repairs involving rangefinder and shutter-curtain replacement, not to mention light-meter issues, etc. Just how old can one generally go before the cost of repairs and maintenance overtakes money saved on purchase price? And how much would you pay for a decent M5 or M6 that will not be held as a collectors item but used on a regular basis?