It also makes for a challenging game if your army is NOT balanced (Ravenwing etc.). Then you will have to improvise with different missions.
Back on the subject....
You definatly need anouther tactical squad or 2, or 3.... They can create support fire, assualt troops and a screne all in one battle. And maybe another Rhino, or a Razorback for some trasnport/support stuff.
That's all I can think of right now.