I completely disagree with oldmansan's opinion. I live in So. Cal. and drive my supercharged Elises in the hottest conditions. I have never noticed them becoming, "heat soaked," and I drive them incredibly hard - lots of times in 100-degree weather with the a/c on max.
The factory supercharger spools up instantly. A stock supercharged 2011 Elise will run right with a non-modified intercooled 2011 Exige 240, as it weighs 36 pounds less than the Exige (factory specs are Elise 0-60 in 4.3 seconds and Exige 240 in 4.5 seconds).
Both of my cars now have Stage 3 (or supercharged Stage 2, if you will) exhaust systems, which really woke the cars up and saves an additional 13.2 lbs. over stock. They are faster, louder, sound like superbikes at high revs, are poppity (especially when cold) and generally much more fun to drive.
Yes, if you plan to race and want maximum power, the aftermarket superchargers are larger, but if you want instant power, the stock supercharged Elises are the way to go. Not to mention the rare factor. If you keep these cars stock (Of course, I saved the stock mufflers), they will only continually go up in value, where most modified Elises will not. IMHO, you cannot make a better investment than a 2011 supercharged Elise (only 51 were imported to the U.S.A., including special editions). Finally, if you PM me, I can give you a list of the cars I have blown off on L.A. freeways.