I've been using the Trig22. The head unit for it will fit in that same panel opening as the Becker. But the guts of it (shown underneath the head unit in that bundle pic) can be placed in a plethora of more convenient places, taking up less space right behind the panel.
That Trig bundle would give you everything you need for ADS-B Out, aside from actual wiring and a transponder antenna
Remember that "In" is basically a totally separate deal – however, to ensure that the ground antennas are transmitting where you are, you (or someone near you) need(s) to be broadcasting "Out".