It seems to me that the GUI change was a bad decision. I have been using SE as my sole 3D design tool for ten years and the change of GUI has resulted in loss of productivity.
This has made me to looking at replacment for SE. The most likely candidate is SW since it supports chain of tolerances...
On www.igus.co.uk you will find over 7000 various polymer bearings under the Iglidur trade name. It is a German product and they have special material for subsea use (ROV's etc).
I have specified Ra 0,2 um on some PEEK sealing surfaces. This is not achieavable by milling, only by polishing. This is a time-consuming operation that could increase cost a lot. You could also try heat treatment using the same 'lighter trick' normally used on scratched CDs, but PEEK has a much...