We've had one up and running with AutoFresh in one of my showrooms for a month now. Sound is great, and we've sold SEVERAL Autofresh systems on new and pre-existing spas because of it. Haven't sold any Aria's yet, but its configuration should be a good seller.
The music system IMO is mediocre at best. Watkins has already been there done that with the original TR Caspian and the fidelity was lacking then just as it is now, including all Caldera Aquatic Melodies systems. Watkins is at the top of the list when it comes to building a quality hot tub, but they are far from the top with their attempts at music. 
Sorry Watkins. 
Clearly the sound is subjective. I don't think it is the same system as on Caldera and the old Caspian, as there is a subwoofer now. To me the sound is good. Customers like it. The FM even works in the showroom, which my Jacuzzi stereos never did (when we sold Jacuzzi).
Price should be about $1000 more than the Vanguard.
Dan, I must have a more sophisticated sound pallet than you! 
If you enjoy quieter music, then the system sounds fine, but it still has a problem at higher volumes. I'm speaking of the Arias music system, not the Spaudio II.
All I need is something for my Jimmy Buffet CDs.
My complaint is the Aria does not have an IPod port yet.
