The ones you have now (AT831)SP CMC 2 are really good and i'd say equivalent to others like CA-11.CA-14 , AT853,AT943 .. those are the other ones SP sells named SP CMC 4 (AT853) and SP CMC 8 (AT943).
I don't see there being any improvements there.
Better to improve your post processing techniques and recording location.
Got any samples of your recordings your unhappy with?