I have an '06 Class A GulfStream with the V10 and like it a lot. The '05 and down V10's had all kinds of engine issues (spark plug threads being the big one) and apparently the transmission can give some grief too. The '06 and newer have a 5 speed automatic and I really like mine. First gear is deep and gets you out of the hole, overdrive has enough rpm if you want to go fast or cruise at 55mph to get respectable fuel mileage. At 50 to 55mph I get around 13 to 14 mpg with mine, any faster and it drops to 10mpg or less.

There is a hp difference between Class C and A, the C's are 310 and the A's are 362 and 457 torque. The torque is okay, really leaves you wanting to twin-turbo it, but it moves down the road on the flats good enough. The V10 likes to rev and makes great power when you put the boot to it.

Check your tow ratings, the frame on mine (F53 Chassis) is massive and I put the big Dana 150 in it so I could put 22.5 wheels on it and still is only rated to tow 5500 pounds. I tow an open-car hauler with an E-Body on it and that is the limit. The frame and diff can easily tow more, but I doubt the engine and transmission would last long if you went over the 5500.

Tiffin is a high-end machine in the Class A's, I can't comment on the C's other than to say I would never own one after having an A.