there are several factors that go into how "sporting" a flyrod is
first of course is rod weight. i find 2-3 to be good small trout rods for small streams. i have landed a 24" brown on a 2 wt with 6x tippet but it was a 45 minute fight and the fish did not survive to be released. 4 is an excellent all around size for eastern trout, but i use a 5 when i need to make longer casts especially when it is windy. i have used a 6wt on many occasions out west. anything less would have been useless.
the size of your fly also makes a difference. a fly rod casts the line and not the fly with most small trout patterns, but when small mouth fishing we throw some big flies and i will step up to a 7wt. my 2 wt can not throw a stonefly or streamer pattern worth a darn. if you envision using bigger or weighted flies..use a bigger rod. the really small rods are best suited for small dries and nymphs
the leader/tippet size is also very important. most people use too small a leader and it can not "turn over" the fly well and they often compensate with a bigger line wt. using a smaller terminal tippet will greatly increase the sport as you can not manhandle fish on 6x or 7x tippet
i generally use a 8'-9ft rod (regardless of weight) as they are better casters in more varied conditions than the short rods.
i once had a 7' 3wt rod for small stream fishing but found it to be of limited utility except for really tight conditions.
my small stream rod is now a 2 wt thomas and thomas. it is best used for dry flies when a very gentle presentation is required. even 6-7" trout fight big on it. panfish feel like tarpon.
my winston 4 wt is versatile enough to use on small mountain streams to big tailwaters. it can gently cast a midge but also deliver a big weighted streamer. it would be my recommendation to you. it is a bit light to take on bass though. i have landed a 27" 5lb rainbow on it but 12" stockers are still fun to land on it as well.
