I just built a house and used trusses because I have a floor plan with the
kitchen/dining/living room all open.
There is a 32' open span that couldn't be done with ceiling joist/rafters.

--
JerryD(upstateNY)

So much for old vs. new construction. Could a free
rafter roof be as solid? Sure, I have no doubt. Lot's more expensive
lumber. The big bonus as far as I'm concerned with trusses is the future
flexibility with floor plans. Want to move a wall? No problem. Most
interior walls are non-load bearing so just knock 'em down and move 'em. As
far as the "particle board" I-joists, I doubt a toilet over flowing once (
or even a dozen times) is going to dissolve them. And if you've got that
bad of a water problem, you've got some serious problems! They got a bad
rap early on, but the adhesives have vastly improved in the last ten years.
A good analogy is the world of automobiles.