Since we have you here, Mark, have you ever seen a Draper Radiant/Contrast Radiant screen? I, for one, am not praising my HCHP screen :-P I absolutely cannot live with its texture. But there are times (when texture isn't apparent) that the screen does disappear and create a 'window' effect. But this depends highly on the source material as well-- the source has to be a clean, sharp, low grain image. Softness, grain, and other artifacts really pull me away from this 'window effect', which is why (I think) I only see it sparingly.
And, yes, in really bright portions there are times I can sort of see a bit of sheen to the HCHP material. But nothing like the Black Diamond, which is utterly horrible (to me). And nothing like the glass-beaded screens (e.g. GrayWolf), where I see it as soon as the image gets even a little bright.