I have had an LLC sub account for years without paying pro fees. I have not charged any fees to sub accounts though so I can't weigh in as to whether charging your sub accounts fees will change this. What I was told (and I assume is true since I haven't been charged pro fees) is that since the master account (and data subscriber) is not an LLC, you do not pay pro fees for data.
Thanks SSB - that's encouraging. I'm not planning to charge fees at all so it's only the existence of an LLC account being controlled by a non-pro FFA account. I really don't want to pay $150 / mo or change brokers.
Unfortunately, the definition of pro limits non-professional access to "Natural Persons". Here is a link with the NYSE declaration form. Look at the top of page 2, section2. http://www.igmarkets.de/content/files/exchange_agreement_nyse.pdf So an LLC account that has access to live data is a pro account, even if it is single owner LLC for someone not in any professional financial services capacity. In an IB financial advisor account structure, the sub-account does not have access to the market data anyway (the user who logs into the sub-account cannot see live data). Accordingly, the sub-account is completely irrelevant for the pro/non-pro question. The FA sees the data. If the FA is a natural person (not an LLC or legal entity), and meets the criteria stated in the declaration (items 2b, 2c), then non-professional status is possible. Any commission generating relationship between the master and sub account pretty clearly makes the activity "professional".