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Title pretty much says it all. Currently there is no way to cleanly move your BEF settings from Views 2.x to Views 3.x.
Clearing out the issue queue... The BEF 2.x and 3.x branches have diverged enough that implementing backward compatibility is a huge undertaking which I don't have the time for.
Unfortunately, the solution is to rebuild your BEF settings after you've migrated your views to 3.x. Sorry to not have a better option...
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