We've had our '07 40Z Tradition for a year and put 10,000 miles on it. I attended the Spartan week long class and brought the chassis up to snuff for $4000.
If the chassis and drive train are in good shape the problems we've had are mostly house related. On an older coach that is to be expected. He's what I've had to deal with in the 1st year.
Dash air - replaced compressor and dryer
Roof AC - replaced both AC capacitors and fwd AC fan
Aft furnace - replaced the power circuit board
Brake lights - replaced the bulbs, they were a pain to get to.
Steps - just broke and am in the process of diagnosing it.
Refrigerator - defrost heating element broke
Batteries - replaced due to age
Windshield washer motor replaced
Air dryers assembly replaced due to leak - by Spartan
I'm able to do most of the work so the cost was not so high, I probably would not own such a complex vehicle if I couldn't do this stuff.