I have been using the Lind EXXtras since before they left Michigan (or was it Wisconsin); I stocked up on a 2nd pair when they went to Mexico. I have not tried any of the ones made overseas (I think they're now made in China, but I'm not 100% sure.) WHatever.
I like that you can change one of the 4 on each sole and 3 different ones on each heel. That degree of flexibility is very good.
Just about the only thing I did not like was that your weight pushes the insert level with the surface of the leather sole. On one extremely sticky approach I still could not slide. SO I found these "lifts" made of velcro the same diameter as the insert and put them in first, then the insert. The lift raised the level so that even when standing on the sole, the insert stays above the level of the surrounding sole. The lift is just double sided velcro: hooks on one side, loops on the other, and they're glued together. I'm sure they're easy to make.
One thing I did do is make my own inserts. I bought some teflon "chips" on ebay, which are the same diameter as the insert. When an insert was worn out, I used a razor blade to cut off the sliding material of the old insert and used contact cement to glue the teflon chip to the base of the old insert. Now I have a new, more slippery and longer lasting slide. I use 1 - 4, as needed for the approach. The teflon is much harder than any of the other inserts and so, lasts much longer. But dirt and tiny fragments of all sorts of crap that alleys never clean up eventually get embedded in and scratch the teflon.
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"None are so blind as those who will not see."