Harvey Hoover did an interesting study of this on this site:
http://www.pelicanparts.com/techarticles/914_BMW_calipers/brake_calc2.htm
Basically, from all the discussion this subject has gotten on this site, it seems to come down to "feel". I have no idea if the 19mm is going to "feel" better but I know right now I don't like the "feel" of pushing the pedal to the floor!
I do know that I will "feel" a whole lot better being behind the wheel rather than under them when I get this car back on the road!