I would have to agree with keeping the Ecotec. It is actually a pretty good, reliable engine. Mine is already hitting 180k with the only major part I've replaced being the water pump (the oem pump was leaking). And that is with me always mashing the throttle. It still does not consume any oil. As far as hp, it only has like five horses less than the 2.4, which can easily be resolved if you wanted. Gas mileage is very good as well. When I try, I can get 35mpg.
BTW, if you want much more power, for less than the price of the engine swap:
Bwahahahahaha