Nine foot five-weight is the universal size trout rod for the western half of USA. Our store sell more of this size rods than all other sizes of single-hand rods put together. That is because the universal fly rod fish are trout that average from 1 to 5 pounds, and the universal flies are from #4 - #20. A nine foot five-weight rod will fish them all. Four-piece is the universal break-down configuration of rod for travel or domestic use.
Five-piece rods are 5.4 inches shorter when they are put away in a case, which meas that their case is 5" shorter. Modern ferules don't interfere much with rod actions or casting energy flowing through them. If there is any down-side to 5-piece rods it is that they are a little heavier and they are more difficult to carry when they are in two pieces, because each half is a different length. Performance and line-speed are nearly the same for 2, 4 or 5-piece rods. If you travel and like to carry your rod on the plane with you, then consider that this 5-piece rod fits in an overhead compartment.