Regardless of how many pre-amps, Sonosax has fallen behind, much like Nagra. Both are scrambling now to produce recorders/mixers that can compete with the digital non-linear offerings of SD, Zaxcom, and Aaton. This isn't a bad thing, more competition is good, but when you look at 4/8 channel hard drive recorders Sonosax is about 5 years behind. SD was able to pull off getting into the game on price/features, Nagra has so far failed pretty miserably (but you can never count them out).
Because a lot of these units are used in films and wireless mics are starting to be used more and more, the emphasis recently has been on increasing channels using line inputs. You have the Cantar with 8 tracks, Zaxcom with 8/10 tracks (16 coming later this year), and so I would expect SD to have something in the works to compete with the growing number of channels.
Wayne