This is my OPINION... Im a fly fishing guide.
Theres more things to consider then simply rod weight/length. Ill be the first to say I believe drag IS an issue. Especially when you may hook into some large smallies and just cause you target smallies doesnt mean a 15lb species of other fish wont hit your fly.
I personally fish a 9ft 8wt for two reasons. One, if I hit a large fish I know I got the rod to man handle it, I dont want it to run around and build up lactic acid which may kill it if you release it. Two, I want to use it for other species such as steelhead,salmon, stripers(although a little light for this).
Buy a reel with a disc drag, so what if you invest $100 or more youll be glad you did when that one LARGE fish doesnt get away because the gears in your drag got smoked. I also suggest a large arbor reel for this kind of fishing, 500 revolutions or 100 to get the fish in... you decide!
One other thing people forgot to mention is action, well, i saw it mentioned but not discussed. Are these creek fish? Is the water clear? If you go with a slow rod you will see that it will protect your tippet/leader during hard runs and or hooksets. The downside is a slow rod has a learning curve that you should prob get used too. A medium fast will give that backbone to punch flies and will sorta protect flies. The Tip flex... fast rod will let you wing out 80-90 ft cast.
Invest the money if youre serious, you dont wanna get sick of the rod and buy another one in a year.