Brat front end geometry is 100% all wrong for performance driving, esp on dirt. As suspension moves thru its range there is major camber change....in the wrong direction. As suspension moves thru range of steering, it gets even worse, esp at heavy steering angles, which since Brat understeers like a piggie, makes things pretty much unmanageable. Of course you CAN drive one enthusiastically in the dirt and have some fun but if U want a decent platform for rallyx, pick something else.
Short answer to question, "Is Brat any good for rally?" is....no nope non nein nyet nunca never, save yourself the grief.
(sorry Bratman)