I'd say from the 60 kids in my CH Chabad elementary grade maybe 5-8 are off the Derech.
I fully agree with Dan's sentiments about living away from the costs and the different culture found there. I tried living in smaller cities for three years. First I loved it but after a while I just started missing the action in NY. What can I say. Maybe I should try something in the middle like CLE
There is such a thing as being too small. I wouldn't live in Kansas City where there's no chinuch and no restaurants unless Sprint decided they wanted a new CEO.
But cities like Cleveland, Chicago, Baltimore, etc. make for a pretty happy medium IMHO.
Pittsburgh wouldn't be bad if it weren't for the decrepit housing infrastructure in the jewish community and the shocking lack of any restaurants.