The thing about burnas with the unit of kommandos is that its usefulness is completely dependent on what you are versing or what the situation is and with snikrot the options just grow. I have never played a game where my kommando's WITH their burnas have not proved their usefulness. Whenever I vs IG they like to stick their heavy weapon crews bunched up around the table edge to lob shots at me, shame because that is when 2 burna templates gets rid of the entire squad with ease.
Yeah ok, I just killed a heavy weapon squad or 2 oblits, the sqaud still costs me 200+ points the way I play it, but its the amount of points that the units I just killed don't get to take off me. A few oblits in the corner? no problem, you got some power weapons to take them out, and if you don't kill them first turn? who cares! oblits not shooting at me is almost as good as them dead. A heavy weapons crew causing you grief? no problem! drop some templates and hit them with your sluggas then charge them, they are as good as dead. Same thing applies to things like snipers or even fellow infiltraters, just pop up behind them, one thing someone doesn't expect is to infiltrate a bunch of their own guys and the templates drop on them by some guys who appeared next to them when they are wrapped around the table edge.
You know much more about what they can do than me, but mathammer aside, and common sense in place, a kommando is just a boy, and to take out squads of enemy infantry it is dealt with my squads of 20-30 boyz not my 10-15 some-what pricey kommandos, they are meant for dealing with the nitty gritty things that would take my boyz 4 turns to finally get to and put a stop in their works. But this is a thread about the effectiveness of burnas not kommandos in general, so I'll end with, kommando's are a versatile unit, you add snikrot and they become even more versatile, you put 2 flamer templates/power weapons and they once again become more versatile, if you don't think they are worth it, don't play em, but I know when I write my list my hand automatically begins to form the word "burnas" when the word kommando is written down.