Do you even know how long it takes to get a colossi or a HT with storm?
And i've actualy been pylon warp rushed three times alredy in my base, and i always won (it's not that hard to spot a probe going in a corner of your base), everytime i just ignored the pylon (so he thought i didn't see him) and i didn't destroy it, cuzz i actualy wanted him to warp units in. You just build defencive units (you are alredy rushing marines) and atack at the right time , and kill all his units that he alredy warped in and the pylon (it's a masacre for the P

). And after that you have a huge advantage over him, any you can go straight to an counteratack, and kill him of with ease.