Hey Michael,
I've had my M1078 for ~6 months...and I've been pleased with it.
My learning curve on this truck was pretty steep compared to my M35A2...especially not having ever driven something with air brakes.
It drives like a school bus...i'm still not used to steering with the air cab bouncing...so 45mph seems to fast on 2-lane back roads.
It took me several months to get the parking brakes, and rear brakes, to work...I miss diagnosed it a faulty air brake chambers (~$240 each, new), but all the chambers need was a 1ounce dose of wd40.
One tire & wheel is 350lbs, lugs need 450 ftlbs torque.
The tires have a large volume, you'll likely want a large air compressor, if the CTIS is NOT working.
I also had a cracked front housing on the CAT 3116...apparently, after rebuilding the starter, the mechanic forgot to tighten the air compressor bracket bolts on engine block ($850 for new front housing, $100/hour CAT labor rate, ~$4k total repair bill).
Also, my truck weighs 9 tons...but you could probably shed 5k lbs by removing the bed.
Cheers,
Tom