The GRA was against it. Talmidei HaGRA do not say it at all. It creates a hefsek in listening to the uninterrupted bracha. With the brochas that we hear we are yotzeh various things (like making 100 brochas a day). BTW, even Sefardim do not say BH uBSH when they hear someone make a brocha shehakol or mezonos on food, which does not follow their shitah! (As per Shulchan Aruch OC 124:5 they SHOULD say it!)
