I bought a new SME 10 back when they were $6,950. I upgraded to a SME V arm and put it all on a Mapleshade platform (see virtual system). Recently upgraded the cartridge. Speed stability and build quality are superb. Once set-up properly, it stays that way. Very small footprint and easy to operate. I would not hesitate to buy one used. It would be a great value for the money ($3500-4000).
I've heard two Scoutmasters in different systems (Magico with Nagra, and B&W with tubes), but never the Aries 3. Difficult to say what the TT's contributed to the overall system sounds, but images were more stable and focused and rythm/pace was better, more involving to my ears with my SME front-end.
Just one more opinion, but if you already have the SME arm, I would add that the synergy of the IV arm with the SME table would seem to be a good combo.