Back on point, though - she recognized that she actually had better control and a more solid/better break with a lighter cue instead of a heavy cue, like people seem to think.
I'm sure there's some study that would corroborate that. And my intense research on the subject (you know, using Google.com) shows a few links of interest.
Bottom line it seems to be personal preference and you'll need to test this out for yourself which is better for you.
Me? I prefer controlled break over power break. My break cue, while not super light like my friend wanted, is around 18 ounces. I have tried heavier cues over 20 ounces and they do NOT work for me nor help me break better at all. I lost control of the cueball pretty easily with a heavier cue, which is not good for my arsenal. I prefer a controlled break where I can squat the cueball in the center of the table. And a lighter cue helps me accomplish that.
Hope you find the perfect-weighted break cue for yourself! Trial and error, baby. :)