Hi Len,
I was much more comfortable w/mine after looking at the DME download and comp test and a PPI from another dealer. Search previous recent threads and posts from myself and others and you will find a lot of info and varying opinions.
It will always be caveat emptor irrespective of CPO or whatever, and no information from any post should sway you from what is right for you. If you're concerned, do it, but if you're not, don't ..... I just didn't want to look back and I wish I had.
Cheers and good luck