Re: Engine life of the 2.4 vs 3.5
The ecotec is a very solid engine. If it can have 1000+hp on the stock block, I'd say it'll hold it's own. Having owned a 3.4, and knowing that the 3.5 is very similar, I'd opt for the ecotec. The 3.4/3.5's aren't bad engines per se, but the 3.4's are notorious for having LIM gaskets leak, and it's almost guaranteed that the 3.5 will have problems as well.
With regular oil changes (and gasket replacements on the 3.5), both engines should last well over 100-200k. I would give the ecotec the advantage though.
'09 Malibu LTZ
Black Granite Metallic
Capitalization & punctuation is the difference between "I helped my uncle, Jack, off a horse." and "I helped my uncle jack off a horse."