Having had the Scoutmaster, and having upgraded from the stock JMW 9 to the JMW 9 Signature, and if I were in your position, I would consider a 3rd option: keep the SM, upgrade to the 9 Signature arm (700.00 if you trade in the stock arm), then invest in a Walker Precision Motor Controller. My reasons for saying this:
1. You say you feel limited by the 9" arm. The added mass of the signature 9 arm and the much better wiring make it far more compatible with a wider range of cartridges than the stock arm. The essential design of all VPI arms is on the unipivot. The longer the arm tube from the pivot, the chance for loss of rigidity. If you look at the audio press reviews of the JMW arms - some feel the 9 series is the best of the bunch.
2. The Aries 3 is a radical redesign of the Aries series. I'm not sure I would want to jump into a new table design it's first year out (kind of like buying a car in it;s first year on the market), but, that's just me.
3. I had a chance to compare side by side, the Walker Motor Controller and the SDS on my Scoutmaster, and the Walker was the better all the way around.
For the same 2200.00, you would have the Scoutmaster with the JMW 9 Signature tonearm and the Walker Motor Controller.
With this combination and a really good cart (Shelter 501,901 or 90X), you will be in vinyl heaven for a good long time.
I lived very happily with this exact setup until circumstances gave me the opportunity to upgrade to the Walker Proscenium Gold Signature table (but I did keep the motor controller that I used with my Scoutmaster)