I replied with a neutral and "politically correct" response earlier as you will have many people on both sides of both tables you had listed.
In my personal experience I have heard both and at the price point felt the Spacedeck with Ace Space arm was quite a bit better than the Scoutmaster. So much so, I now own a Spacedeck.
I have heard others argue that you can throw money at the VPI on upgrades and exceed the performance of the Spacedeck and Ace Space arm. That may be the case, however I felt at the $3,000 range the table should do certain things well enough without further upgrades. I chose to spend the rest on a decent phono amp and cartridge. (Whest PS.20 & ZYX Airy 3S-SB) ...
However, the best advice I could give is stated above - go listen for yourself, if you can find a dealer that carries both. I was lucky enough to hear both the Scoutmaster, the Spacedeck, and the Michell Gyro SE in the same system. Granted, one hade a different cartridge, two were the same and setup may have been more dialed in on one table moreso than the other, however after multiple times listening in various areas, the Nott Spacedeck with the Ace Space arm was preferred over the others I listened to...
Good luck on your search.