Folks,
It's a combo of some, but not all of these things, and one other possibility.
Alex, are you talking about the visual appearance of the prop blur ie if the dark graphic areas slowly/quickly rotates as the prop spins, or the darkness of the spinning sections of the blur, or the overall clarity of the whole spinning disc?
Z, with some models the prop blur is also affected by the clarity of the prop blur material itself, and not just the texture (but most of the time you're right that it's the texture).
S, The prop ani ratio setting will affect the visual of the slow spinning cruise speed prop graphic and ac speed, but it will also affect the speed of your ac. If you make the ratio higher the ac will fly faster (and slower and the ac flys slower). If you want to have a faster visual of the prop spinning you can adjust it by 0.01 or 0.1 + or -, you can have a play with numbers, but just not big chages otherwise it will affect ac speed.
Cheers
Shessi