Ehab,

That wasn't my experience with my Roo at all. Off of grass with a RAM750 at 12 pounds thrust (detuned) I was off easily in 300 feet. The trick with the Roo is to make sure the back of the turbine is pushed up about 2 or 3 degrees so it's not driving the nose into the ground (which keeping brakes on will do right from the start) and also make sure the jet sits nose high on the gear anyway.

My take off procedure was simply no brakes, advance to half, once it's rolling go full power and in about 300 feet apply up elevator and it would come off no problem at all.