I've always wondered if getting your eq to it's maximum if it would "force the issue". It would make a little sense but it doesn't seem to be the case as BPFSL and bpel increase the same amount as you make gains.
Basically, BPFSL is just fun to look at and a lot of people like to use it to measure gains. The reason given is it's more accurate. I don't really understand, but whatever works.