Remote??? ... Radio systems consist of a transmitter and a receiver ( in English ). The expo and dual rates are functions found in the transmitter ( if those functions exist at all ) to be specific and not the receiver which only does what it's told by the transmitter to do.
It's pretty important when asking a technical question that you use the proper terms so people that are trying to help, don't get the wrong idea and then give out wrong information. I believe everyone here did understand that you were talking about the transmitter but I have seen misunderstandings in the past and try to point this type of issue out early when possible.
I'm with the others, I believe Futaba is the only maker that uses expo as a negative value. I understand why... to slow the response, you take away from the amount of input, hence they used a negative number.