Bottle fed babies do often get to a 4 hour EASY before a breastfed baby, and often need to go to 3.5 hours before 4 hours. The problem is they aren't able to do the A times until they are around 4 months so you run into problems like feed times falling in the middle of sleep times if you push the feed times too soon.
I agree with PP on the night sleep - that's fab and the day calories from the 3 hour EASY are probably helping that, so I'd stick with it for a while yet! Also remember that he won't always take the same amount at each feed, that's quite normal!
Laura