I don't have the ZF6 but REALLY wanted one until I got my 2010 F350 V10 CCSB 5R100. I'm surprisingly happy with this truck. I bought it for $14k @ 70k miles. It now has 121K and is worth about $20-22k in this truck market three years later.
She's a working gal. She got named "Sweaty Betty" on a trip from SLC to South Lake Tahoe by an advertising friend riding with us a couple years ago. I get 6.5-7mpg with this load and trailer. I get 8 mpg with my silver "Jeep" on a single car hauler. 11-12 mpg commuting and about 13 mpg running about 75 mph on a straight interstate run without a trailer. The name fits all to well. It's a great truck. It comes with a cost of fuel vs a deezel. It does not have DEF, a turbo, expensive injectors, etc. I've never been able to get the mpg out of whatever deezel pickups other folks have but the deezels I've had all get about 9-12 mpg at worst towing this kind of load and get about 14-17 mpg on highway cruising.
As for how the do with that load, much better than I expected. I expected to be 55 mph climbing out of Moab and possibly even less mph on other 7500+ elevation mountain passes. I can top out of Moab at about 65-68 mph and worst mountain passes I'm about 60-62 mph with that load or similar. The climb from Carson City to South Lake Tahoe is about as steep and windy of a highway as I've had it on and it did as well as the 7.3L Excursion I was towing with. We had different powerbands and I'd want to pass him in some spots and he'd want to pass me in others. Just as we were trying to sort that stuff out, he started hitting temps in his trans and I slowed to just stay behind him. In my opinion, the V10 compares well and is a good truck. It's not a deezel and never will be. I'm confident it'll do the job you want it to but you'll need a gas card. I'm trying to talk myself out of my truck and trail Jeep and into a Gladiator. Not sure it'll happen as I don't want a payment at all.
(I've had '99 7.3L, CCSB, '01 Excursion 7.3L, '04 2500 Cummins {pile of shit with an awesome engine}, 2001 7.3L, '98 2500 Cummins and now this 2010 F350 with V10-4.10 gears) The '99 7.3L would be my favorite truck and this V10 is a very close 2nd. This truck just works. I think the manual would make it a little better (I have the 5r100) but for an auto, this is a good trans to tow with.
Bonus for this new of a truck: GET THE INTEGRATED BRAKE CONTROLLER