As a counter anecdote, in about ~15 years of using mechanical keyboards I've never had one fail. I had a daily driver for 7 years that was good as new when I eventually gave it to a friend.

Couldn't agree more about the other two points though. To go along with your second point I would also strongly suggest looking for a keyboard that is hot swappable. You can use a switch tester and all that, but only actual experience will tell you what you really want, and I think very few people end up sticking with the first switch they have. A hot swappable board will let you alter the switches without replacing the whole device.