I'll unfortunately have to agree with Spoon. There has always been the question of "balanced armies"... "balanced units"... etc..etc... this is fairly much an "unwritten rule" of the community.
However, a "rush" type army is a legitimate army and has been used by everyone not only in this game but through history. Ever hear of Blitzkrieg..? (spelling)
Because someone cant or wont defend against a "rush" army doesn't make the rusher "unfair"... it's up to everyone to compile an army to withstand "all" types of attacks. If one cant accept that then maybe it's time to rethink your army.?