Not sure on the tmag, but i rode an onza bird 2009, and it felt waaay short for me, i rode a zoo python long at the time, which is more than 1020mm, so i felt there was a difference, im 5'8" or so, some people say they dont feel the difference, but believe me, i definetly did
edit: its all aobut preference, how tall are you, people that are say, 5'5" or so, would ride a short, but like i said, im 5'8" or 5'9", and i ride a long, feels gooood to me!
good luck mate!