I had the heels replaced back in December. I wore them walking for 4 months, mostly on pavement and wore down the heels some so I put the heel savers on. I have not found they cause any significant loss of traction.
I am going to do a video on the heel savers. I put them on a bunch of shoes that have heel issues.
The shoe goo seems to work pretty well as an adhesive, but I suspect there is no glue that will deal with the flexing and stress where that crack is on the sole.
It was an interesting experiment though.
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Warning - I am not an expert on anything having to do with this forum, but that won't stop me from saying what I think.
Bob