I've pretty much decided not to leave the government right now, although I am still curious about other's experiences.
I don't have the complaints others have. My agency is reasonably aggressive about implementing change (at least compared to other agencies), I have a decent amount of autonomy, a lot of work from home flexibility, and I get paid very well already.
There is always the issue of whether the grass is really greener elsewhere. It can be frustrating watching coworkers get by while doing very little work, my job is certainly not exciting, and my group in particular is a little dysfunctional these days, but I think in ways that are not unique to federal work. I do have the option of switching to a different division within my agency - there are many and each has its own culture - but I have a lot of flexibility where I am right now and I don't really want to walk away from that.
I think in about 3 years I will probably have the opportunity to be put up for a 15K raise in my current office - not sure if that would happen in a different division. That's about the pay raise it would take to get me to walk away from the feds and go private, which I'm not sure is realistic anyway. If I wanted to pursue a traditional career, it would probably be a good move for me career-wise to go private in a few years for advancement purposes, but of course I don't want a traditional career! Just before early retirement, it may be a good move, but I will have to reevaluate then. I have skills & exposure that private companies are very interested in currently -- its possible down the line this will be less in demand but I don't really anticipate that.
I am also concerned about being in a position where I am expected to be motivated by the company's bottom line, because I don't really care about that at all. I also am not motivated by prestige or feeling important. I am motivated by the greater good, which is something that my current job contributes to at least somewhat. I think it would be harder for me to find that motivation in the private sector.