As said above, I also think the difference is more neutral in the DR, for example my FIL uses a lot of the expression "en el barrio they said this and that", simply referring to the neighborhood where they live, which is not poor.
Personally I?d consider barrio to be something where people know each other better and spend time hanging outside on the street, whereas in urbanizacions they tend to be more locked up in their homes. There well might be exceptions, but this is my observation. I?ve only lived in barrios in Puerto Plata, and to be honest would not even consider living in an urbanizacion.
I have no idea why is this so (some people say that it?s because the areas are on a higher ground), but again, what I have seen, is that better barrios do get served better in terms of electricity and water than poorer barrios (unless they are in the same circuit) or urbanizacions. Again, I?ve lived in barrios 5+ years and during that time, we have had to order water truck exactly once (cost of full truck 400 DOP), last summer during the worst drought.
There are programmed electricity blackouts, but they seldom cut it outside of these programmed times, and in our case it has always been max. 12 hours weekly.