I get this question all of the time. The fact of the matter is that you can cut holes big enough in an I-joist big enough to put ductwork in.
According to the latest Random Lengths lumber market report, prices of framing lumber has been increasing. For contractors, this means you need to keep higher prices in mind when you bid on your next job. For consumers, this means you should start your do-it-yourself projects as soon as possible.