I have not had the opportunity to hear the Scoutmaster at home, however, I think I can give you some informed input on the Spacedeck. The Spacedeck is the sweet spot in the Nottingham lineup IMO. Better than the models below it with diminishing returns for the dollar above it. Don't waste your time or money on the heavy kit either. For whatever reason, the standard Spacedeck has the magic. Also, I don't care much for the Nott arm. I got much better results with a hot-rodded RB600 with Incognito wiring and OL Structural Mod. Adding Pete Riggle's VTAF improved the focus and bass.
The Spacedeck itself sounds much better than it has a right to sound. It responds to arm changes, mats and other tweaks, for better or worse. My current setup includes the Living Voices Mystic Mat, VPI weight and Graham B-44 Phantom arm. Many would think I'm crazy to use such high dollar accoutrements on this table. They have been incorporated over time by careful listening and the Spacedeck allows these devices to shine.
If I were to have to choose between the stock Spacedeck/arm and stock Scoutmaster/arm I'd probably lean toward the Scoutmaster. I feel the Spacedeck delivers black backgrounds like nothing else in it's price range. Unfortunately I feel the Spacearm kills it. Just my opinion.