I went from a 39' TT to a 39' 5'er. THe TT towed just as well as the 5'er because I was using a Hensley hitch. While you do loose a lot of bed space in the truck towing a fiver there is still some usable space in front of and behind the 5th wheel hitch. The fiver basement is huge and makes up for any space lost in the bed of the truck
Height of fiver can be intimidating. You do need to be more concerned with over passes and tree limbs. On the other hand the higher interior ceiling are nice and make the 5'er feel more like a home and less like a trailer.
THe fiver tows a bit shorter vs. a TT. A good 5' or so over hangs the truck bed vs. a TT. Otherwise they are both just as easy to maneuver and back in.
I strongly suggest a 1 ton SRW truck as a minimum if you plan to tow a 5'er . you will need/want the additional payload vs. a 3/4 ton.
Pick your poison. I prefer the higher ceiling and additional storage of the 5'er, however there are lots of nice TT floorplans I could live with as well. There will always be more space in the 5'er.
