I knew I read this somewhere. And I agree with Bruce about having used something that's worked "just fine" for so long. I'd like to add that the more I read and the more I use something new, the more comfortable I become. I remember going through this with my first cordless drill! Geesh! I couldn't believe I waited so long to get one after they became so popular. Now that I've been using one for years and really like it, I wonder how I got along w/o one for so long!
Anyway, Here's a UMASS 'study' of the subject you ask. More and more I'm reading about products that are 'stronger than regular wood'. I-beam construction is a relatively recent product that has undergone 'change' in wood composition. Wood composite I-beams are supposedly stronger than traditional wood I-beams, so I read. Good luck! Check out OSB vs. Plywood.