Caution, the contents of this post are highly opinionated and somewhat stubborn in nature.
The last thing I'll do is to debate with a guy who makes his living selling fly rods, but I will share some personal observations. I have fly rods ranging from 6'3" in length all the way out to 15' rods. Regardless of what person at which shop would tell me, an 8'6" rod would be the best tool for fishing small creeks I will tell him he is wrong. That statement I'll stand on until I can no longer crawl and clamor through the bushes and over the rocks along 'small' creeks. If you go fishing often as I have been fortunate to have been able to do for my whole life, you figure one thing out for sure. While I was out there exploring my state, my country, and the continent, with my fly rods in hand the guys behind the counters who were telling everyone what rod or reel worked the best were just that; behind those counters.
I'm not saying that being in a shop filled with the very latest and best that the tackle manufactures have to offer does not impart some level of expertise but if you are asking me about the right rod for a small stream............... and you really mean a small stream.......... You can bet your last dollar I'm not going to hand you a long rod. Maybe I'm really misguided and have been doing this all wrong all these years but at least I was out there doing it day after day and not just telling people how to do it.
Perhaps that all sounded a bit harsh, or defensive, or self embellishing, but when I think small streams I'm thinking small streams. There is no way to swing an 8'6" rod on the same streams and spots I fish with my 6'3" rod. If there were why have I been using the tiny little rod when I could have had an 8.5 or 9 footer in hand. I think the guy at the shop is selling the rod he likes to people who are asking for guidance. I somehow figured the length thing out on my own by fishing small streams.
Small creek = short rod,
I'm done, sorry