All,
All Extra's (except the first 230's)are certified aerobatic, monoplanes, some people (Patty W.) put a cover over the front place, and fly from the rear, ala edge540(not 540T). The 300 is the basic AEIO-540 powered mid wing. The 300L is the low wing version of the 300. The 300S is the single seat version, w/ shorter wings and fuselage. The 300XS is the same as 300S but w/ experimental control surfaces made bigger for high aoa flight.The 330extras are just a 300L/S/XS w/ an uprated, high compression, blueprinted AEIO-540 that is producing 330+hp. There is also the Extra 260 that was produced but I dont know much about it, I think a smaller single place airframe w/ an IO-540(260 hp). Also the Edge540 is an off shoot of the 300S, a composite company owner said he could build a better wing for the 300 from composites and did it, the wing was so good he decided to build an entire airframe and boom Edge 540.
Clear as mud..Good
PS Some people have said that CAP's have extra300 wings, this is not true Extra made the wings for some CAP's built to CAP specifications.