the only thing the diesel has over the gas in the longevity department is the engine itself. everything else bolted to it is does not live longer than gas components. In fact, most components attached to the diesel engine will fail long before the gas parts. IE,... injectors, emissions related components, fuel filters, etc... the 10 speed tranny is unproven, the 6 speed is....
at resale, yes the Duramax will bring more value. but you also pay nearly $10K up front for it. I just did a quick KBB comparison of trade values for my truck with Duramax, vs gas 6.6. The trade and retail price difference was $7k. so in reality, diesel does not even bring the initial cost back to trade or sell.
I love the diesel, but will be going gas next truck. with all the issues they have, and my needs, it just doesn't make sense anymore