Of course there are some disadvantages. A longer rod will be heavier. Not much, but somewhat. Also, if you fish smaller streams, a longer rod can make it difficult to cast in and around tight spaces. If you do any dapping, a longer rod can make line/fly control difficult. If you're dapping and need to suddenly move your fly closer, you have to elevate your rod at an angle, which, with any wind, can cause you to lose control of the fly.