I just bought a Markins M10L head that is SILKY smooth at low frictions, but for some reason I expected it to be silky all the way up to high friction. Closed down with the D2H, 300 2.8 AF-s II mounted it's not very smooth and feels a little gritty (not like sand gritty, but like cloth). Is this normal? Other than that I love it.
I'm not really sure what you mean by "cloth gritty" but my M10 is very smooth, even when closed down. I'd suggest that you contact Markins, I've found them to be very responsive.
My M20 is smooth without tension and with friction applied. I had this and the RRS BH-55 and found that the M20 was much smoother under tension (for the samples I had at least).
Hmm by gritty I mean, that compared to when the ballhead is in loose tension, under tension, it feels as though the ballhead itself isn't smooth, there are very minute microvibrations as if the surface is bumpy. Kind of like the difference between running your hand over smooth marble and over fabric.
I think what you are describing is normal. Under no tension, my M20 is completely smooth. I actually never operate the ballhead like this. I normally set the tension to the desired level and always keep it there. With tension (enough tension that my setup doesn't flop when I let go of my camera - at reasonable angles, of course), the ballhead is definitely not as smooth as when it was under no tension. I still consider the operation smooth and I would never describe it as gritty.
