Real world, most with a V6 can get better gas mileage than with the V8...IF, IF, IF the V6 doesn't have the factory tow package. Tow package on the V6 changes the axle gearing from 3.55 to 3.73. If you have friends complaining about V6 mpgs, they probably have the tow package. V8 tow package (however) gets to keep the 3.55 gearing, since it has a super-low 1st gear with the standard 6-speed auto. V6 still gets the old 5-speed.
To more easily find a 4th-gen truck with the V8, expand your search to Mountaineers, too. I found it much easier to find a V8 Mounty in decent shape, compared to a V8 Explorer. And in my search, I could find plenty of top-end AWD Premier Mountaineers, for less than an Explorer 4x4 Eddie Bauer. The prices on the Explorer Limited 4x4 was rediculous. The only thing I don't have is a low-range transfer case, which is fine for us.