For those who came in late, the whole point of BrewBri(gh)t(e) is that it is a dual purpose kettle additive, consisting of a mix of carragheenan and PVPP. The first element flocs out the hot break, leading to clearer hot wort out of the kettle, and the PVVP flocs out polyphenols that can carry over into the finished beer and cause chill haze.
I like BB because, as pointed out above, if you add it right at the end of the boil, it flocs out big crumbs and flakes that head South very quickly. With Whirlfloc I didn't notice this happening and the continued 10 mins boil, if anything, tended to break up big flakes into smaller flakes, so why bother.
However the second component, in my experience, isn't
always effective against chill haze, I've found. I almost always do ales nowadays and notice that some of them are a bit hazed at say 2 (say if I've got a bottle chilled in the fridge to take to a club) but nice and clear at serving temp of around 10. It's a bit hit or miss, some beers do this, others - such as my wheaties which I do serve very cold - don't seem to be affected.
And none of this has anything to do with yeast haze which is best solved by a few days in the keg at most. I haven't used gelatine for a while.
I like BB because of its spectacular action in the kettle, and I still keep some Polyclar VT as an insurance policy only, for example if doing a comp beer which is going to be served cold. Otherwise the chill haze component is secondary to me.