One thing where I believe the Qt app is worse than cocoa app is the control sliders, you can't just click anywhere on the slider and start moving it, you have to click the knob, which feels a lot clunkier to me. Could you make the slider draggable from any position @masc?
Maybe those who like cocoa app would be happier if the Qt version had a simpler theme, but that isn't really a big deal for me.
As for Cocoa app coming back, probably not. It's currently in a bad mess and doesn't work fully (the last release is about as good as it is going to get). It's just too much work for what it does - it was written without XCode, no interface builder which I think Apple never intends anyone to do. Also written by me with no clue about how Objective C works (the real issue).