Thanks for that info, CaptainKB. I checked out the EMS socket system. It looks similar to other elevated vacuum designs. I hope it's working well for you. $15k is pretty steep unless (mostly) covered by insurance. (That was almost the price of my last complete AK pros.)
I did get an token email reply from Otto Bock Canada. The SiOCX will not available here for a few more months. Of course, they would not talk about price, just "speak with your prosthetist".
I will definitely follow up on this and post again when I have more info.