A recent experience I had was when my usual TY supplier sent me some Acu-Disc white printables to try with a glowing endorsement. Suffice it to say that the PlexTools plots made yours look excellent, there was no C1 'grass' at all, just solid fills in either green, blue or red (quite a lot of red, actually).
You won't be surprised to hear I didn't buy, with the caveat that the tests were done at my usual 8x and it's possible the A-Ds perform better at higher speed. Sorry to hear of your TY woes, Ed, perhaps you inadvertently got some of the fake ones we hear of from time to time - I'm guessing it's too late to return them for a refund. Rock on, PlexTools!