Hi Mattressprotectorguy,
There has only been a couple of other comments on the forum about the Crypton mattress protector (here and here) so I appreciate that you took the time to share your thoughts and experience about them as well 
I know that Jeff from Mattress-To-Go had one to test but he didn’t like that there was no absorbent material on top of the Crypton fabric so any spill could roll right off the protector and down the sides of the mattress so he gave it away and decided not to carry it before he had a chance to test it for breathability and I think that runnerb0y’s comments were written before they actually had a chance to sleep on it (although they were hopeful about it).
I haven’t tried it in person but I did order some samples of their fabric and they didn’t seem very breathable or flexible to me either (although they were very waterproof) but the samples they sent me may not have been the same thickness as the fabric they are using in their protector.
Phoenix