And i think Ketsui would work with a trackball...
No way. 'bullethell' SHMUP's are unplayable with a trackball. Those games need very, very short response times togehter with very accurate position moving in horizontal and vertical direction, sometimes over small distances, like a few mm's, sometimes over large distances. You can only achieve this with a good joystick with a short throw, like some Sanwa and Seimitsu sticks. For certain games these sticks are superior over any other one. Here is some more details about these sticks:
http://shoryuken.com/f177/sanwa-seimitsu-faq-118289/So just forget about a trackball, because although you probably can place your ship very accurately with it, it is much too slow to handle. Besides, (almost) all great SHMUP's originate from Japan, and should only be played on Candy Cabs, and they would look redicoulous with a trackball.