I know this breaks the "3 gates or less" condition for new gates horribly, but it would make a very nice addition for compact builds.

A logic gate that would be able to read Buildcraft gate conditions of the block against its base (set via a GUI), and output a redstone signal to wires connecting to its sides.

Additionally an advanced version, which would connect only to bundled cables on its sides, and would be able to check N gate conditions, outputting signals on specified wire colors.

...Just use gates.