I've had a '24 for just over a year now. Until Friday, things had been great in regard to reliability. I went in for an oil and fuel filter change and ended up coming home in a loaner vehicle. Somehow, the variable vein actuator broke on the turbo which through a bunch of codes when I started it to come home from the dealer's service center. I have my doubts that it was a coincidence but apparently there is a technical service bulletin covering this (I've been searching but haven't found it yet).
As for how it tows (I have a 40' Cedar Creek weighing in around 17k pounds), I've been quite happy. Power has been quite good with the exception of torque management from a stop (extremely aggressive in 1st gear). Once it hits about 1600rpm the power comes on all at once (again, only 1st gear from a stop though). Drivability in every other situation has been fantastic.
Mileage towing my trailer is 8-9mpg on the highway around 65mph. Not sure how the other user pulled off 23mpg around town as I can only muster 22mpg on the highway under 70mph if I'm focusing on driving with mileage in mind. Around town, we're closer to 12mpg.
Overall, I absolutely love the truck and I would have a hard time parting with it. It's comfortable, I like the creature comforts, and it does its job. If you have fulltime plans in your future, there is no reason to buy a gas engine.