Thank you for the inputs.

I bought the Exotics spacer anyway for $10 as I would have had to some extra spacers anyway, and maybe grind them down to avoid cutting the tube. The adjustable spacer resembles a piece of plumbing ... two hex pieces that thread into each other. It is alloy and the action is smooth. Easy install. I like that part of it.

Unfortunately, I found the stem I bought last winter was for a road bike, and since I didn't want to use handlebar shims to go from 25mm to 31mm, I will have to get another stem. Good thing I didn't have to cut. as I can adjust the height for the next one.