Obviously you do not know the class either. It is mostly DoT damage, and I'm not talking about 55%, it is closer to 70%.
Pay attention to combat logs, and you will realize. Otherwise, if you are not applying your DoTs, you will notice your total damage to be more then cut in half, and obviously showing more lack of knowledge on how to play.
The ONLY part of the burst that can be perceived as OP is just a matter of timings. If you use Thermal det and time railshot correctly you can make both damage hits register at the same time, which can make it "LOOK" like that person was just hit for 8k-9k at once. A sniper can do the same with explosive probe and Ambush, without needing to time, and more often @ less cost.
With the ICD there was actually an increase in TTK for Pyrotech, however small, it was an increase not a decrease, which in turn is a nerf.