We we seriously considered trading our 1st travel trailer, we already owned a 3500 duly (gas). When we traded for our second TT, we seriously considered all the options we had: another travel trailer, a 5er, or just switching gears completely and go with an "A" and use the car for a toad. We laid all the cards on the table, considered all pluses and minuses of each RV.
In the end, the final decision was made, not so much by type of RV, but what kind of functionality would we have for a second vehicle when NOT camping. How functional is a small family car and a CLASS A when one needs to haul a sheet of 4x8 plywood, or move a refrigerator? (or in my case, hauling firewood to stock us up for all winter ... we heat the house with fire wood as a secondary heat source) In the end, we realized we needed the truck more for daily use, for hauling things, and towing a utility trailer more then we needed to have the bed of the truck containing a 5er hitch, or attempting to haul plywood, trees, and building materials in a motor home.
When we got the diesel duly, towing really became sweet. Our third travel trailer exceeded our expectations beyond anything we could imagine. We hit it just right! It's now a good balance between the second vehicle usage for camping/towing a trailer and needs when not camping.
So, in your decision, consider long and hard what happens and what functionality does that second engine really do (second engine... a motor home engine, or a truck engine to tow that 5er). And if go with the 5er, what do you use that truck for when not camping. You may decide to opt for a Travel Trailer to keep the bed of the truck free.
It's your decision in the end. I'm just throwing something more "out there" for you to consider, not trying to twist your arm? What functionality does that 5er, truck, or MH have when NOT camping? This may sway your decision if you think about it?