Thoughts/opinions on these pads?  

I have had mine for years, I love it in specific situations.  I really Love it under my Treeless saddle.  Very happy with the pad, shims allow for flexability

I have 2 of these pads and use them every day.  I have a couple of low withered mares and the corrector pads have been game changers.  They hold up very well, as my oldest pad is 5 years old.  They come with mulitple shims so you can modify for each horse or situation. 

I bought one used in good condition but didn't turn out to be right for my situation.  I really liked the idea of it though.  Lots of options with the pads.