Thanks @Kim. I've felt that lately I have participated less in forum, It is good to be appreciated. I recently moved from my long time residence and the move pulled my attention away from trading for a while. But that is done and I have been able to focus on SO more.
The margin requirements (whether you have Reg T or Portfolio Margin) only determine how much you are allowed to borrow. Regardless of the type of margin account you have, you pay interest on the actual amount you borrow. So if you buy $200,000 of equities and your account has a value of $100,000, you're borrowing $100,000. But if you buy $2,000,000 of equities and your account has a value of $100,000 you are borrowing $1,900,000.