I'd recommend that you go with the 3-weight for river and stream fishing for trout. I personally prefer a 2-weight, as it allows me to toss very lightly weighted nymphs on longer leaders, and makes a superb dry fly rod. My 2-weight can easily handle trout up to 18 inches without having to play them for a prolonged period of time, and makes the typical trout (8 to 12 inches) feel like a fish twice its size.
You have to read between the lines when reading the American and U.K. magazines and books, regarding fly rod selection and recommendations, as they're writing about angling in parts of the world where they're legally allowed to fish multiple flies, with Hopper-dropper setups and multiple nymphs and streamers - whereas a lighter fly rod, in the 2- or 3-weight range, is much better suited for our province's "single fly only" angling regulation.
Anyways, that's my 2 cents on this subject...