I'd agree with the other posts, re. the use of 0.003" or 0.005" foil for windscreens. Thicker than that is unnecessary, and will be getting hard to work.
Of course, it will depend to some extent on your windscreen design. If you use a design that adds rigidity to the foil, such as a cone, or something like my SqueezeBox Stove, then lack of rigidity of the thinner foils will be compensated for by the structural rigidity of the shape.
The Cicerone guidebook author, Paddy Dillon, has made a Ti SBS using foil from TiGoat, and this seems to have been very successful, producing a robust pan support and windshield that doesn't require the careful handling that Al foils require. He sent me a couple of scrap pieces of TiGoat's 0.005" and Suluk46's 0.003" foil, and a folded section of the latter can be flicked with a fingernail hard enough to make me wince, but without any damage at all. An SBS for an MSR Titan kettle in the 0.003" foil would weigh about 42g.
As others have said, Ti foil is much less ductile than Al, and you need to be careful about the minimum bend radii; any attempt to fold either of the above foils back on themselves results in a fracture along the fold, whereas aluminium at a similar thickness would survive, even if hammered flat.