Won't that make it a little too unanonymous though? Yeah you'll have yours more personalized and even easier to remember so you won't have to copy it everytime but i think randomness is what makes btc addresses more secure.
Depends what you want as a prefix. If it has your username then it will be linked with the username, but nothing else. If you use something like 1Bitcoin then it isn't effecting anything. If you are post any address with your username then it instantly gets linked with your account anyway. Adding a prefix and then posting it here on the forums isn't going to make a difference.
