You should be paying professional fees only if you're a professional, i.e. someone working for a brokerage. If you're just an individual trader not working for a firm, you shouldn't have to pay professional fees (even if you trade for a living and it is your profession).
That's what I thought too. But I just signed up for the new Tradestation Pro and I actually read the Exchange definitions and according to it: You are a professional if "you use the information in connection with any trade or business activities." Since I was planning to file mark=to-market status, and I plan to trade fulltime, doesn't that mean that I'm a professional investor. I guess I probably should just ask someone at Tradestation. I was just wondering what other people do.