To hell with Daioh. Too many buttons, not enough fun.
It seems you can get by with just the purple homing, missiles, and bomb of your choice(I go with laser), so three buttons, which shouldn't be a problem..
Also, for people that don't know, it seems the purple shot gives you the most points for hitting enemies. So for popcorn enemies and milking easy bosses you'd want to use purple, while for large enemies and killing bosses fast, use missiles.