I have heard the Spiral Groove once. It was excellent. I feel the Ayre/DPS with Mr. Bauer's tonearm (which I have owned for about a year now) is just as good as the SG and so is another option you might want to consider. Better yet, consider the Shindo Garrard. As good as the Ayre/DPS and Spiral Groove are, the Shindo Garrard is in another class entirely.
BTW - That's one nice system you have!
BTW - That's one nice system you have!