I recently acquired a Current Designs Vision 13.5 hybrid composite and find it’s length to be quite adequate for most tasks. I’m 5’6" and 170 lbs fully dressed with pockets full of stuff. The amount of stuff in my pockets does not effect my height, just my weight.
I also have a Perception Sonoma 13.5 that is quite quick, efficient and maneuverable and great for rivers and scoots right along on lakes, as well.
Both of those boats track just fine for me, but YMMV.
I don’t see a need to go longer for most things. I also own an Epic 16X, but will likely be paddling the Vision 13.5 more than the 16X, mainly because of it’s smaller size and greater ease of handling off the water and transporting on the car top. It’s also more comfortable for me to sit in, but that’s not related to the question about length.