I have the sandals too, I LOVE MY MBT'S!!! I have never seen the rocker bar in the middle with different insoles, are they new or did you get them 3 years ago. Maybe thats it because I've been all over their website and never seen those. Also where did you get them re-soled at? I wouldn't think anybody but MBT could do that.
Have you noticed a firming up of your backside, or a difference in cellulite? Just wondering, I only know one person who wears MBT's it's always good to hear what people think about them. I have never worn a more comfortable tennis shoe or sandal.