I have a '09 Cascadia, that's done very well. Still, I had a wiring harness repair for an EGR valve problem, and a more pricey rebuild of the DPF system after the controller failed. Took out the DPF filter, DOC, eventually replaced the doser. Probably $14k total over 7 years. Had some warranty failures too.
That doesn't include lost revenue.
Mind you, with all of that, I count myself lucky. It could have been much, much worse. One of these trucks that refuses to work properly can easily suck up $30k or $40k of your money - that's bankruptcy level trouble.
On the whole, I like my truck. I'd have to really think about it before buying another one.