Welcome to the boards!!
Each experimental unit has it's own strengths and weaknesses. The Sacred Assault Bot is one of the most leathal ground units in the game. They are extremely costly to build but can turn the tide of any ground battle in your favor. The most important thing is to keep support units close to your experimentals to help compensate for some of their weaknesses. For example, while the Sacred Assault Bot can take on pretty much any other unit in a close quarters battle, but it's range in fairly short, and it can't defend against aircraft.
I've seen numerous players spend all their mass and energy to get one of these behemiths build, but then has nothing around to support it. They walk it toward their opponents base thinking they're going to put the fear of god into their opponent just to see several strategic bombers pound the bot into the ground before he fires a shot.
Keep mobile AA units close by to knock out bombers and gunships that might try to knock him out. It's always wise to have a group of seige bots and mobile artillery when you launch your attack as well. After the last patch, there isn't any one unit that you can build that can win you the game (this is arguable).
Go get SupCom and give it a shot. It's the best RTS game out there right now.
Don't hesistate to come back and ask for some pointers.
