I now have the Tilletts in my Elise, and I can say that from the waist down, they're perfectly comfortable, and from the waist up, they grip very tightly, almost too much around the lats. They seem like they will be well suited to holding you in place on the track, but almost too constraining in the upper back for comfortable everyday use. All this is to say, if you have an opportunity, try them before you buy them. I think that they're probably best suited for a long, thin torso. I'm 5'8", in good shape with no extra weight, but I find that I have to sit up straight and tall to avoid feeling too constrained in the upper back.
Former owner of the great car in my avatar, now with a great new owner: 2006 Elise BRG sport, steel brake lines, RTDbrace, hardtop, black powder-coated wheels, Katana (finally working!), Moroso pan, BOE fuel kit, boost & oil pressure gauges, Blackwatch gauge bracket, Tillet seats, Schroth 6-points, Braille, Xtender, Dunlop Star Spec 205/50, 235/45 street , Rotas w/R888s track