An F150 HD will price out so close to a F250 it's almost not worth it. You get more of everything in the F250, but mpg will suffer somewhat. You could tow what ever TT you wanted with an F250 gasser though, and you probably won't be coming back here posting about sway issues.
JMHO, but after towing a 7300lb 31' TT with a MaxTow (1857lb CCC) and a Ram 2500 there's really no comparison between the two. If you're okay with just getting by then go with the F150. If you want to know that you have plenty of truck and won't be worrying about what you can or can't pack for a trip then go 3/4 ton.
Sounds like your're really leaning towards Ford but IMO a Ram 2500 6.4 will get better mpg than a Ford 6.2 and with rebates will probably be less than ordering an HD F150.
In the end I suppose you could just get the Laredo and tow it with the F150 and if you don't like it upgrade to a 3/4 ton. That would be the more expensive route. Buying a smaller TT would be the least expensive route.
Just to clarify things, I'm assuming you already own an F150?
