BYU led the nation last season in pace of play as measured by the average time taken to snap the ball, and were one of the top teams in number of plays per game. And they want to go faster this season. It does provide for all the advantages you mentioned - tiring the defense, not allowing situational substitutions, etc. But it also has it's drawbacks. As has been mentioned, it seems like we ended up with more 3-and-outs than we would like, and as fast as the pace is, that means we send our own tired defense back onto the field without a lot of time to rest. And while we put up a lot of offensive stats with so many plays per game, our red-zone offense last year was horrendous, and we didn't score nearly as many points as we should for the number of plays we run.
The hope BYU fans have is that in our OC's past stint at BYU, he regularly led the nation in both 3rd down efficiency and red zone scoring. So we hope that with a year of the GFGH offense under his belt, we see improvements in these two areas. I don't expect to be back where BYU was when Robert Anae was here the first time, but I hope to see improvement that along with the increased pace of play, make BYU difficult to defend.