Having read the posts and done the math, it looks like Cosmos' solution of 205/50/16 up front and 235/45/17 rear best preserves the correct f/r stagger in terms of width and maintains the best possible adherence to rolling circumference. Best of all, it cuts my tire bill to less than half with apparently zero sacrifice to performance.
I did the math on the rake and the losses are insignificant. Going to this setup from the *ahem* TOURING
suspension, there is only 1.25mm of rake lost and from the LSS package only .5mm of rake loss. Considering the amount of rake is only 10mm to begin with, maybe that's more significant than I think, but I doubt anybody's car is going to suddenly be rendered a kite (a la Mercedes at Le Mans in '99).
BTW, I just received my new Rota Torque rims (16x7, 17x8) and neither the front or rears have those stupid superfluous extra holes! (and yes they are the correct rims w/ the correct offsets for the Elise/Exige).
Bought them from A Spec wheels on ebay, $549. Haven't installed them yet, just put on a new set of AD07's on my stock rears, because I still have more than half of my fronts left. Went through the first set of rears in only 10 weeks, 10k miles. They were slicks when I took them off.