It's an interesting question.
As one who started out here in Park Slope (in 1996), then migrated ever downward through Windsor Terrace to Sunset Park -- following which, I had to leave Brooklyn altogether for a couple of years because I just couldn't pay the bills on three jobs -- and now living in Prospect/Lefferts Gardens, I think it's fair to say there's a trend -- and not a happy one.
The natives, I suspect, are growing both restless and wary. Many parts of Brooklyn just ain't what they used to be. Sure: there's still Canarsie and East New York. But at some point or other, the risks begin to outweigh the advantages.
E.g., I was mugged and robbed three weeks ago in Prospect Park at 7:15 p.m. on my way home from work at Slope Cellars. I've spent much of the time since then -- when not on the job (thanks to some sympathetic employers who chose to let me continue working) recovering from wounds and recovering my stolen documents. I'm afraid I have to confess: walks through Prospect Park -- even by broad daylight -- just ain't what they used to be.
I may opt in 2013 to leave Brooklyn once again and not return. My kids are now out of the nest, and my former wife has moved to Manhattan. I'd like to be a Brooklyn lifer, but not if it means living behind bars -- even if those bars are only in my head.