Figured I'd post an update since I've been having a steering wheel vibration when applying med-heavy brake pressure at about 60mph -> 45mph that I believe I finally solved by upgrading to the M3 front control arms this week.
I had suspected a bushing failure after some reading online but couldn't say for certain until I had the old control arms off. On the drawing below, I identified a shear failure of the bushing marked as #15 on my drivers side. It wasn't a total failure, but it was enough to prevent the bushing from properly transmitting load. Note: the way these bushings are loaded and the way they fail makes them impossible to identify failure simply by grabbing them and "twisting". I wouldn't have been able to recognize this one without actually taking it off and looking at it.
Even in just the 20 miles I've driven since the install I can tell all the vibration is gone. I'm confident that bushing was the culprit.