[slotloco]

Interesting and quite thorough test Brian, thanks for taking the time to compare and share.
I hadn't heard of the urethanes vs. rubber supposed incompatibility debate before.
Personally, I cannot see how one would affect the grip of the other, unless one was pulling "rubber" off the track, or the urethanes were leaving dust marbles behind
-  so again, thanks for being so thorough. 

Those results indicate they will do well on wood in an "untreated" environment before the witches brews come into play.
[ as you say, that is a whole other alternate reality, "sliders"  seems an appropriate term :) ]

I wonder if others can give us some similar information on Scalextric, Ninco, Policar, Carrera tracks.

BARacer - Those that apply secret sauces will have an alternate reality. The G25 doesn't take the usual aliphatic solvents and oils well, so those folk will rue the loss of F22, N22, Hi-Grip and the old Ultragrip like the loss of a favourite pair of socks.
I know one sicko who has stockpiled over 100 mixed packets of the above items like a panic buyer gathering toilet rolls the night before Covid lockdown.