Nen:

While I don't disagree with what anybody said; these days a lot of trout fishers are afraid to fish anything bigger than a 4wt. Years ago; trout fishermen fished 5-6-7 weight rods with impunity. The trout haven't suddenly evolved in 50 years to the present and now have become intellectual giants that won't touch a fly thrown on anything heavier than a 4wt. As a matter of fact; I'm have two 5wt's being built for me right now and I'll use them any place and catch lots of trout.

Trust me, I throw size 24 flies just as delicately with my 5wts as I do with a 2-3-4 weight rods on some of the spookiest creeks there are. It's all about presentation. If you have a problem catching trout on a 5wt; believe me, it ain't the rod. In other words; think about throwing the bigger stuff being the problem; not the small stuff.

If was strictly trout you were targeting; maybe a 4wt would be best but throw some bass in the mix and you couldn't pick a better line weight than a 5; the "OLD" standard.