As far as the bike goes it will be most competitive in Ultralight SB, but you will be racing against the occasional Expert that runs that class due to being combined Ex/Am.
The other classes are all about the same bikes in the class but running Am and there would be no competing against the Experts as far as trophies goes. Thunderbike, LW GP, GT Lights, and then in 6 years LW F40.
Mark