I'm replacing some rotting hardwood joists in my deck, and I was wondering if treated pine might be a better replacement timber? These joists get rained on, and that is why the hardwood ones rotted in the first place, as far as I can tell. Would treated pine actually last longer? (I saw one post saying that you can get treated pine guaranteed for 40 years these days!)

These timbers won't be in direct ground contact, but will be weather exposed, as I mentioned.