The firebomb I felt was the best way to exemplify my point that it's to overpowering to do it this way. Made my point didn't it? ;D
You will as soon as you show why it's perfectly alright for firebombs to breach power armour.
Other than that, I prefer to have "superior" weaponry (bolters, plasma and melta weapons) to use their penetration against toughness on a 2:1 base.