Those are interesting "drain holes" DD, good thread. I was reading a special issue of Cycling Plus last week and for winterizing bikes they recommend drilling a drain hole (as you said "literally") in the bottom bracket for the actual purpose, including on aluminum and CF. Keep the water from pooling on the bearings and spindle was their reasoning.

I'm going to do this to my CAAD 10. They also recommend spraying a preservative in the BB shell and the frame tubes. Wonder why you don't see these anymore? I guess with cartridge bottom brackets mfgrs don't think its necessary like the artisans did.

Bill