I went with a 5.5' bed this round by choice, not by what was available.
6.5' bed is only 1' longer obviously but it determines your turning angle but also gives a longer wheelbase for a better ride and tow experience.
For my needs, I camp in small camp sites that you need sharp angles to get into. My home driveway is the same as our road is really about 1 1/2 lanes wide and my driveway is 1 lane wide. I have to do almost a jack knife to get my trailer into the driveway.
Having a longer wheelbase would make it much harder to maneuver into my driveway let alone the camp sites I like to get.
The bed size addition in a 6.5' length is insignificant. If I was a contractor that needed to move plywood sheets and dry wall, I wouldn't be buying anything less than a 8' bed anyhow.
I've been able to haul and move everything and anything I've needed without problem in my 5.5' bed so having a 6.5' bed gains nothing but inconvenience maneuvering my trailer into my driveway and the smaller camp sites.
I originally wanted a 6.5' bed for a truck cap to maybe camp in, but realistic it would be too hot and cramped to be comfortable next to an open and airy tent. Then if I'm not camping in the Jay Flight, I'd want to use a tent anyhow to get deeper into the woods where I couldn't get the truck anyhow.