I've had a bit of experience driving cab-overs; we have 2wd Isuzu dumps and most recently we purchased a 2012 Mitsubishi Fuso 4wd.
The Fuso is 4wd, so it sits up incredibly high due to the solid front axle, this makes getting in and out quite an exercise. Ours has a an auto/manual transmission - I would recommend going with a manual transmission, if possible. The auto has been real finicky, especially during the first 2,000 miles and especially when towing any sort of load. Lots of random downshifts where the engine revs and the tach jumps real high. In the beginning the truck seemed to shift haphazardly - winding all the way out before it would shift. The truck is also really jerky and seems to have a fair bit of lag. There is no tow/haul mode, but there is an exhaust brake. Fuel economy seems to hover around 11-12mpg, with the highest I ever saw being 14mpg.
Our setup is with a 10' bed and a behind the cab toolbox; it's been loaded pretty good and doesn't squat too badly. We have a plow for it, but have yet to try plowing with it - I'm not looking forward to using it.
The 2wd Izuzus are tanks. They're much more peppy. They have 12' beds and can haul a pretty good sized load. I much prefer the 2wd to the 4wd. Again, towing with a load (skid steer) is a little bit of a struggle.