Thank you

One thing came to my mind, I don't like Xel'Naga Towers but I love the idea implemented in Xel'Naga Fortress. Simply, it destroys in time(around 5 in game min.?). This may helps to aware you if an early cheese coming, 6 pool or some kind of an very early all in. After that all is depend on your scouting ability which is good, at least some skill involved.