The Challenger is great, but lets not forget about the Holmes. A little heavier than the Challenger but there was many a Holmes frame on the AA gate in the early 90s. Even if it didnt have S&M stickers on it!
Dave Clymer and Todd Lyons were both happy on a Holmes (21" tt, same as the XL Challenger), but they would tend to do backflips in the motos, enter the Jump comp before the mains AND go street riding after the race .... all on the one bike!