The plan, as I understand it, is that M::B will become part of the core starting in 5.10. At that point, there will be a push to have all CPAN distros migrate to using M::B vs. EU::MM which has been unofficially deprecated.
In the meantime, I use M::B with the traditional flag.
My criteria for good software:
Does it work?
Can someone else come in, make a change, and be reasonably certain no bugs were introduced?