The situation, as described, has lots of good things: sane hours, sane people and more than enough pay to live on (80K is a long way above the median income for families in any state). I spent several years in a situation that had some of that and I'd do it again in a heartbeat. Especially, since I've been through the other side of it, and ironically, at the same place. I worked in a small group, had ownership of what I did, and my manager asked me to do something specific about once/month. As long as I kept finding things to do, and I didn't go too far off the beaten path, we were good. That wouldn't work with everyone, but, with the right group it could and did work for the most part.
It's interesting that some immediately go to why it can't work. I have no doubt there would be pain, problems and other issues, but if you had the right people, in the right places, you'd have a shot at it. Growth would probably be your biggest enemy because you'd have to resist it (or raise prices) or risk diluting the situation.
Hard at times but well worth it if you pulled it off.