It sounds like you are worried about trying the pro stuff. If so, cooking one category makes sense if the organizer allows it. I think you answered the question in your original post: it's up to the organizer. Most contests will charge you a single fee for all the categories, but if you found one that doesn't, great.
If you jumped right in you would find pro isn't so bad, especially if you have done a backyard before. We skipped backyard, and started right out with pro. We got calls in our second contest. (Took 40 more until our first GC, but hey...) Don't be afraid to pull the trigger, we all started there. Cook the pro, have fun, see how you do. Remember Pro is somewhat of a misnomer, it really means it's a KCBS sanctioned 4 meat event. Most of the teams are hobbyists and not making a living at competitions.
