Hi, my son is almost 4 months and we are trying to switch him to a 4 hour schedule as well. (I'm also a working mom, pumping like crazy!) I've been told to do it gradually to see how he takes to it, making up for the ounces lost out of that one feed throughout the rest of the days feedings.
It's strange because he seems to have lost complete interest in eating lately. The more moms I talk to with babies this age have said the same thing about the eating habits. It doesn't seem to have affected his sleep so far. (I probably just jinxed myself)
We also do a dreamfeed, but at 11. For a while he was waking up, like he knew it was time for that feeding. He did that for about a week and then stopped. Also, when he would wake up to eat around 2 or 3am I tried the pat shush thing to see if he would go back to sleep without a feeding and it worked. I was worried to try it at first, thinking I was depriving him of food. But I figured if he really was hungry, he would have really been upset.