A month in, and am still finding new sounds with my Siggy and loving it! Lately I have been particularly struck by how well they sound clean in the middle with both on full humbucker. Split one or both definitely leads to some great acoustic-like clean sounds, but the unique balance they've achieved via the asymmetrical shapes is really apparent with both on full. I can't think of many dual humbucker guitars that sound so lush, balanced and three dimensional in that middle position.
The 57/xx variants are definitely great at this as well, but man does the Siggy sound exceptional through my d-style amp since there's no breakup, it just stays clean. Really great for arpeggios, and chord-melody jazz lines. It's really a unique sound, and just so fun that you can always just flip to the huge bridge pickup when you want to rock out. As others have said, I would definitely characterize the bridge as pretty bright, which I just kinda dial out as needed - though might not be everyone's bag.
Anyways, everyone here already knows this, I'm just catching up Definitely makes the Paul's Guitar or Brent Mason model very intriguing with the narrow 408 at the bridge. The BM seems like amazing bang for your buck - you get all the 408 flexibility, but with the ability to get the Strat quack positions. I would think these guitars would be making an impact in Nashville or Austin scene (along with the DGT, of course) if you can somehow get people's attention away from the ubiquitous fenders in those areas.