>Barring severe budget issues or personal lawlessness, I could not be fired or demoted. But, I'm also at the top of my scale, which means I can't be promoted either. It doesn't matter much what I do (or don't), I can't go up, I can't go down. I'm just "here".

>In some sense, that's supremely freeing. I can put in exactly as much effort as I feel comfortable with, learn new technologies and techniques right up until I don't feel like it anymore, and so on.

>On the other hand, I'm kind of a lazy guy who works better when there is a boot up my rear. I know in the private sector I would learn a lot more, and grow professionally a lot more, because there is always that "up or out" mentality.

Spot on. Personally, I have thought about this a lot and came to the conclusion that I would rather have the flexibility and breathing space to work on side projects rather than having a high pressure, long hours job be the only thing I can focus on.