Hi Joey:
I'm not sure I fully understand your question, but let me take this stab: The tax rules, including deductions, are the same for a proprietary trader who is a member of a LLC as for one who is trading either in his own name (as a sole proprietor, filing a Schedule C) or for a trader who is trading in his own LLC. The same tax items of profit, loss, deduction, credit and so forth will be reported by the taxpayer, albeit on a different schedule (Schedule C) if the trader is a sole proprietor
Same rules any way you go, and no tax advantage or disadvantage to a proprietary trader in a LLC vs. the other ways mentioned.