Sorry if that's not directly related to your question, but I'm testing Tecco (german brand) canvases on my R1800 - they got a matte one (Canvas Pro Plus, 340g/m2, 520µm), and a "satin" one (Canvas Satin, 350g/m2, 410µm) which is rather glossy, more than satin.
It's basically a matter of taste, but I feel that the reflections on the glossy canvas really kill most of the picture, except maybe in very controlled gallery lightings... because with the canvas structure, there is always a reflection in any part of the image.
For me, it explains how hard it is to make a convincing glossy canvas - hope this helps!
The matte one is quite pleasing, otoh.