i use a $75 sirui l10 head, its a knockoff of the RRS tilt head, but its still great quailty.
and yes once resized smaller the pixel compression of a 36mp d800 helps with masking soft images. at 100% you can tell, thats why i would rather use the 1.4 and crop, at 5.6 i cant tell 500mm alone vs using the 1.4 most of the time. also autofocus works much better, and was better contrast and less CA