Hi hambeak
The hall I visit occasionally is poor - middle class. I notice that there does appear to be some seperation between the poorer and better off members. They're all nice to me as I'm probably still classed as an 'interested one' so I don't know whether my observations are entirely correct!!
I do however find your suggestions apply to the mainstream churches though. Every year here, there is a door to door collection for Christian Aid and it has been noted that the largest amount of donations comes from the poorest areas of town.
I think maybe when you are/have been poor yourself, you have more empathy for others in a similar or worse situation. The empathy pulls communities together. Whereas if you've never had to ask anyone for help, you don't need to make those connections and can remain superficial.