My own experiences with my central air pump and with other pipe/pressure/flow applications tells me that once the distribution pipe is big enough, bigger doesn't make it better.
OTOH, for people who can use rigid pvc and have lots of outlets, the price delta between 3/4" and 1" is small enough that there's little reason to not use the larger size.
I'll agree with what's been said about the necessity of bleeding off excess air and the benefit of a loop distribution system when it's reasonable to do things that way...