Well, just a quick thing about BB:
People always talk about how it's useless because any good player always checks their flank and blah blah blah, but really, besides regulars, how many consistently good players do you encounter? We get a lot of pubs on OCR, which means I'm able to pull off stuff like backburning three medics clumped together behind a single heavy in the matter of one second.
I don't use Back Burner all the time because it's really a situational weapon, but when the situation is "the other team has crappy medics and I can flank them over and over again," you can bet that I'm going to use Back Burner.
Plus I love the sound of stuttering crits.