I know throwing money at a problem isn't usually a good solution, and while the 7d is a good camera, that or indeed any crop camera at the moment is really not suited to 25600 iso. 1600-25600 ranges were indeed practically unheard of a few years ago. Apart from the money issue to upgrade and the loss of field of view with existing lenses if you have a bit of an issue to get detail with existing kit, it might be worth while downloading a trial version of a few noise pluggins or standalone programs and see which one does the best job for you with minimum effort