Kage2020 said:

I can, of course, speak only for my own experiences. Ideally, I'd like to claim that my approach doesn't change significantly whether I'm writing for my own amusement or for an assignment, but I've been more willing to delve deeper with my assigment work, to think about things I wouldn't necessarily have considered by myself, and do things I might not otherwise have attempted, because I've had an external source of focus.

I don't ascribe any particular difference to the potential for quality - anyone writing RPGs professionally has their talents whether they're being paid to use them or not - but I wouldn't necessarily say that writing professionally has 'shackled' me in any way. Quite the contrary - the process of being assigned material means that I've had to look for inspiration, where fan material seldom is seldom so driven, as it draws more upon people doing what they want to do at the time and what they're comfortable doing. Simply put, professional work has challenged me more, because with fan material there is no inherent incentive to push myself.

Again, this is per my own experiences, and in no way represents anything but my own feelings and opinions on the matter.