I've got one with a C9 and find it an adequate engine. The C7 is pretty small. I'd probably not choose one for myself but I've been accused of being an engine snob and requiring too much engine to be satisfied. What is the hp/tq rating of the C7 you are looking at?
210 HP was all I ever ran in my 26000 GVW 24 foot Sterling. It gave me 11 miles to the gallon and did me a good job.