lesschumras-
I assume your question is not being answered because people here don’t know all of the issues involved and don’t want to misinform you.
I remember that when the Flatbush eruv was first put up – I think about 20-25 years ago – our rabonim told us not to use it and mentioned some reasons why, but since then I basically just remembered the “no” as far as using it and moved on. When the Boro Park eruv was put up, I asked a Boro Parker why people who didn’t hold of the Flatbush eruv used that one, and he told me the reason was the elevated subway lines that almost completely surround Boro Park. I did a quick google search of “flatbush eruv problems” just out of curiousity and found many issues discussed that I wasn’t aware of, such as population density for example.
These vague recolections and explanations by non-rabonim are the reason I am uncomfortable discussing this issue as if I know authoratatively what the issues are.
pearl-
I appreciate your concern, but I have no problem with Joseph’s question.
I see it as if I am schmoozing with someone during my work commute, who when it turns out we may have a shul or something else in common asks me where I daven, send my kids to yeshiva, and so on.
Since this is a public forum I declined to answer.