The last hurdle on PRISM seems to have been addressed--the invention of a pressure transducer that is robust enough and cheap enough to make the product economically viable.  Based on what I have seen, the development  is proceeding steadily and successfully.  It works.  It works well.  Yes, I wanted it five years ago.  The difference between the decade+  trek to certification of TCM's FADEC and the long trek to certification of PRISM is that TCM kept it quiet much longer!  On that basis, PRISM seems to still be ahead of schedule.