Well, I only heard each for a short time: the SFs at Innovative audio in NY & the big Kharmas at GTT, but here goes...
The SF has nice purity, but just sounded weak & thin overall. They just seem to be holding back too much. It was pleasant, but kind of boring. I had a similar feeling about smaller SF (Grand Pianos) I have heard. The Kharmas had much more life & were very transparent, with a very nice sense of flow, with each instrument well defined in it's own space & having a unique tonality. But take my advice with a grain of salt, as I own a pair of Kharma 3.2FEs, so I am very famililar with the Kharma sound. The little Kharmas integrate the bass better than the big ones, but the bigger ones have a more smooth, open, grander sound, that is very relaxing on classical music, but still very involving. Both the big & little Kharmas have a tranparency too die for.