A Wally Tractor arrived today, and combined with the Wally Skater, I took both tables into good light, made sure they were level and did my best with them. The WS has already shown me that the anti-skate setting on my tonearms is very accurate, and today I learned that the single point SME protractor is also infinitesimally close to the settings at multiple points demanded by the WT. This is good! But one issue occurred: the cantileverless Decca Reference is really hard to set up simply for lack of clearance under the cartridge body. A strong light behind it and a pair of magnifying goggles are useful.
It all sounds good, as it did before...
The funny thing is that I really like the simple HTA adjustment on SME arms, where one racks the arm back and forth with an angled hex-screw tool, but despite how easy it is to move them just so (much easier than sliding the cartridge bolts in the headshell), I did not need to move them much at all. I bet if I had cartridges with exposed cantilevers the WT would be the dog's b*ll*cks.
I also have a Dr Feickert protractor, and I think I can say that the Wally Tractor is both easier to use and likely a bit more accurate.