I don't get the hub-bub, it's just another 2nd stage. Actually, they've kind of been going downhill IMO. The best was the pilot, then the 109 aka balanced/adjustable, then the D300/350/400, then the G250, which went downhill with the 'upgraded' G250HP, then the S600, then the unfortunate X650. Sooooooo......to me it's a little tough to get excited about a 'new' SP 2nd stage.
In fact I was just sitting at a light pondering why I don't just get rid of everything except a few balanced 109s. Okay, I'll keep one pilot too. And a few D300s, but only because I have a bag of poppets for them.