Did you just ignore me? D=
I answered you directly above!
It's a good question. I can't give you a straight answer myself.
I used to really favor using it as a dps CD but I'm on the other side of the fence now.
The reason? Spamming Snap Punch too much will wipe your buffs (other than GL3 of course) and you may end up doing less dps in the long run because of it.
Using Dragon Kick after PB will not give you the debuff (or refresh it if it's already on) and Twin's buff will run out if you don't include it in your PB rotation.
Twin - SP x3 - DK can work as a dps cd AND keep all your buffs running, but you compromised two GCDs for the buff and it looks less attractive as a CD.
On the other hand, using it as a starter saves at least 15 seconds of less than GL3 dps. That's pretty significant and I believe it's a bigger dps increase than using PB for burst.
However, it's not always better. The primal fights are a great example of where using PB to build GL3 seems pointless since they wipe your stacks fairly frequently when they jump away. In these cases, I believe using it as a burst CD is, in fact, better.
This is my burst rotation:
Dragon Kick (IR) ---> Twin Snakes (Blood for Blood) ---> Demolish (Steel Peak) ---> Touch of Death (Howling Fist) ---> Fracture
Dragon Kick ---> Twin Snakes ---> SP (Perfect Balance) ---> SP --> Twin --> SP --> Dragon Kick --> SP
Good for Titan's heart or Garuda after she summons the twins or whenever for Ifrit.
PB is like the most complicated thing the MNK has to optimize. People really undervalue the buffs because they are automatic in the standard rotation.
For PB, you have to be aware of it though. A Snap Punch without either DK or Twin's buff does around the damage of Twin Snakes while without just Dragon kick, it's around Dragon Kick's damage.
Not to mention, after a SP x 5 PB rotation, you will not have DK for a full cycle afterwards and you won't have Twin's buff for the DK or next Twin.
So those are things to keep in mind when deciding how to use it.