When I got the NSX, I moved my 7 or so years NCB from the MX5 to the NSX and moved the MX5 onto AON - which, as it didn't require any NCB for a good price was a good move.

Strange your insurance is so much; mine is garaged with a thatcham class 2 immobiliser, but no particular other things that would make it low risk (except maybe the area? CB1 in cambridge).

Hugo