I have 4 stratas and two reds, the greys are slightly slower than the darker greys and the reds are faster with better feedback to me. the reds remind me of a surgical black in feedback but smokes the arkie in speed. the edge quality I don't see much shaving difference, if any between the stones. I love them all but the reds are my favorite finisher at this time.20x strokes off the coti and I can shave off the stone, still strop the razor well but could shave without it, I did it as a trial. actually now I prefer the red edge to the coti edge, I use wedges most all the time and they are silent and deadly whisker whackers. the reds leave the edge smooth and no irritation or a/s burn or sting at all. all I get is a cold tingle, to me that says a lot and the stones I have from terry are some of the best I have ever used. all I can say to the ones that haven't used one yet don't know what they are missing, 100% thanks to Terry for bring these stones to us.
I did the best I could comparing scratch patterns between the stones up to 100x and there I cannot detect any difference between them until I compare the slower stone .that is where it goes from a scratch to no scratch pattern, almost invisible mirror.so you may be right about the lighter ones just burnishing the edge, but following up on it after the red is the best edge I ever experienced.