The thing you have to remember playing against a PE is that you have to buy time and make him lose as much time as you can.
The 3 eng start is a must. Why ? Because they are cheap and can cover all the map real quick.
If one of your eng squad meets a PE gren squad, don't retreat your squad. Find cover, run behind a buildig, jump in and out ==> fix the PE squad so they have to deal with your eng squad. Try to bait the PE player to follow your eng squads around the map.
Doing that you'll get such dominance in the map control that any build order based on 3-4 rifles, triage/sticky, T4 will win the game.
