@MichaelGrigg I think you’re talking about the way the relay is wired in this image.
I did mine like this. This way you still get to use the On/Off/Logic switch on the power supply to control things.
If I were going to add shop-vac control (which I may in the future), I’d just carry the line from the spindle relay on to the shop-vac relay, one signal to control both.
As to the speed/swaying questions, well the machine can go faster, but it isn’t going to be doing that when you’re carving. If I keep my hands on the laptop, it doesn’t sway as much either.
There may be a precision impact, I haven’t done anything that precise with it yet, and I may have to adjust my plan as I go.
-Kelly