You can add blag to your /etc/apt/sources.list.d/ by adding a file there called blag.list with the contents:
9000/i386 os updates errata
For BLAG10000 (the next major release) I plan on being as compatible with the "mega-merge" as possible. That's the combined efforts of dag/aptrpms/freshrpms/newrpms/dries. See:
I don't think you'll see major conflicts with them right now, just as long as you don't do a
with all of them enabled. If you're going to have a really repository-mixed box I recommend chosing the package from the "authoritative" maintainer of the mega-merge and if it's not in there grab it from BLAG.