I've owned the following receivers: 4000, 4700/4900, 7100, 510, 811, 942, and 622. The only one that gave me much of a problem was the 942. Even the 7100 was stable for me, and I used it for about 3 years.
The rest of them were/are extremely stable and reliable. Still using my 4700 on my 2nd TV and it is rock solid. I think it is about 8 years old and been through numerous software upgrades. Heck, it was even software upgraded from a 4700 to a 4900 along the way.
I've never had a maintenance problem with any of them. None were ever repaired.
The 942 lost recordings, crashed a lot, wiped out my timers on a regular basis, and was generally a piece of junk for the 10 months that I used it.