It's hard to tell without fully assembling the scope and actually pointing at something, whether the new tubing is better or worse (or the same) as the existing tubing. My hope is that the thicker sidewall results in a stiffer bearing surface that has less of a tendency to "stick" when the scope comes to rest.
If I don't notice any improvement, I will try the soap.
I was able to get the scope out for a full night last night with the new tubing installed.
I can say, without any hesitation, that both the friction and the stiction are GREATLY reduced with the thicker, opaque tubing.
However, it turns out this isn't necessarily a good thing. The reduced stiction is great, because it makes pointing/tracking much easier. However, the reduced friction is not so great -- the balance became so critical that simply removing the eyepiece from the focuser caused the scope to drift back up to vertical. That was REALLY frustrating, because I'd find the object I was looking for in my 30mm eyepiece, then try to swap it out for a higher-power eyepiece, only to find when I came back to the scope, that it had slipped several degrees toward the zenith.
I ended up wrapping a bungee cord around the UTA and shimming some rocks from around the observing site under the elastic to improve the balance. However, this was a game of cat-and-mouse: when the scope was aimed lower toward the horizon, I had to remove some counterweight from the UTA to keep it from slipping *down* when an eyepiece was installed. And when observing closer to the zenith, I had to add more counterweight to keep it from slipping further up toward the zenith.
So it seems my current combination (2 well-polished coats of StarBrite marine polish + new base tubing) is ultimately a fail. In the spirit of only changing one variable at a time, I'll try adding the soap treatment next. If that doesn't work as planned, I'll swap the new base tubing for the old one, and if it's still no good, remove the soap (which would put me back to square one).