I need to get some new fly line this year and there are so many new types that my head is spinning. I also just build a new 4 wt. rod so I am also debating on getting one line that will work for both my 5 wt and my 4-wt rods (note that both rods are 9' Pac Bay IM6 rods, the 5 wt is a 4 piece that I use for travel and back packing). Would it be better to use 4 wt. or 5 wt. line for both set-ups? Also I went to purchase the new 5 wt. multi tip line (not available in 4 wt - the 5 wt has one floating tip and 3 levels of sink tip), the other day and the fly shop steered me away from them. They said that they do not perform the same as a single section line. I hate wind knots and tippet hang-ups so if the multi section lines even occasional cause problems then I would prefer to stay away from them.