You can seal those gaps with any type of strong adhesive tape. Even monokote would work if you can get it to stick well. You just pivot the aileron to full deflection and run the tape along the length of the gap. i.e. fitting it into the "v" of the gap. Make sure you don't have any binding.

I doubt leaving it as is will affect your plane that much. I've talked to guys who swear by it and others who don't think it makes any difference at all. Personally, I have a Magic without and a Stik with.

Do a search here on "sealing hinge gaps". You may find more information.

Mike