Flapper,
The beauty of the 3g shoes is that you can use dexter heels and soles if you are willing to do a little extra cutting.
The 3g soles are labelled just like the secrets in terms of slide potential but they are made from much different materials.I prefer to use the dexter sole (usually a red leather) and the 3-G adjustable heel. The heel is a white rubber heel that has had the front edge milled off and replaced with a Velcro strip. You cover this stirp with a piece of the sole material to match how you want to slide...grey felt, cream, white or brown or even the red leather.
If you want to use the dexter heels, you just need to cut out the area for the peg or remove the peg altogether....its only there to keep the heel centered on the shoe anyway. I use a sharpie to trace out the cut then use an X acto knife to cut. You can also use a Roto zip or dremel tool if you have the correct bit. I then use a dremel with a sanding drum to clean up to roughness around the peg cut.
My original tour ultras required me to sand the peg down some. It seems that the 3-G heels are thicker than the dexters......again a dremel with a sanding drum did the trick.
I have convertedd over to the dexter heels and soles because they are far easier to find and most often will be cheaper when you do find them.