Decided to go with the white, non-4K, tab-tensioned, in the form of the Elunevision Titan 92".
Went to Elunevision's demo centre and got a look at their products in person, including a demo of the different fabrics. There is no question that the 4K was definitely better, especially on the whites. The cinema fabric, tended to color bright whites with a mild sepia tone, whereas with the 4K fabric, they were dead on. That said, the cinema actually seemed to get the blacks to be even blacker (despite a higher gain). Note that in practice (at least for the bit of Avatar we watched), the difference was virtually unnoticeable during fast moving color sequences. It was only at the bright whites that the 4K really showed it's stripes, like during sky or sunset sequences.
Went with the tab-tensioned because the salesman said without it, waves and ripples would be inevitable, sometimes even out of the box, and the warranty will not cover them. The tab-tensioned 4K has a cool adjustable tension feature, so you can tighten in over the years as the screen starts to curl, but still not enough to make me pay almost double what I did for the also tab-tensioned Titan.
Will let folks know how it turns out when installed with my Mitsubishi HC5.