Hey, I just tried 0.51a (as I was unable to before), and I must say, nice job on the light gun. Although I have a problem.
I'm left handed, so I'm forced to hold it in a very awkward position. Hopefully your next change will fix that.
And about what I said about the top screen as default, ignore that, I haven't tried the new version when I said that.
EDIT: I have a bug to report. The light gun does not work in pure-soft mode.
@Sir_Voe: For playing on the top screen, you can just hold your stylus at an angle so that the top of the stylus lines up with the place you're touching on the bottom screen. It's still fairly difficult, but it's more accurate when done correctly (plus it adds a slightly different feel to the game).