Do you find that the free software you develop overall tends to provide a better learning experience/more fun/more satisfying than your day job?

It all depends on what one finds satisfying. I'm still very interested in growing my technical skills, researching new and exiting things, being creative, and supporting free software. But in the end I think I'm most interested in how the software I develop affects the people that use it. I enjoy seeing people use software that I've created, and I love it when I see that my software has helped make somebody's job easier or produced a good return on their investment.

That's a reward that you can find working for the man in the commercial world or developing free software. For me it doesn't make it any less rewarding when I get paid for my work, and it fits well within my clients' expectations that I get paid when I give them a product.