I have been following this thread, and am inclined to think along the same lines as weelittledrummer--while sharing a lot of Val's perspectives--

The reasons that you give for wanting to leave have to do with "respect", and the idea that your suggestions on arrangement have been ignored---from this, I am guessing that feel that you should be playing a different role in the band than you have been, and that the band doesn't want it.

My old and dear mentor, Uncle Albert (may his memory live forever) used to say "This ain't a democracy, it's a dictatorship"--and bands are all that way(though most are fairly congenial about it most of the time). It isn't that easy to get a steady gig in a working band--because working bands are fairly rare phenomena--somebody has to make it work--and that means, on ocassion, that somebody has to say, we do this, not this, and everybody else, regardless of personal feelings, has to say, "OK"--because in the long run, making it work is what it's about--

I don't really know anything about what went on in your band, or what was said when the whatever hit the fan--but here are some things to think about--

Did anyone agree with your points?
Did people try to explain to you why your ideas weren't appropriate?
Do others in the band have greater experience and background than you?
Do you feel that you are a better musician/singer/writer/arranger than the others?
Do others disagree with your assessment of your abilities?
Do you have other, immediate, opportunities to perform?
Are there opportunities as good, or better, than the one that you are leaving?
Is the contibution that you have made appreciated?

If the band is a working band, chances are that they can replace you in fairly short order, if necessary, though perhaps not without inconvenience, or regret--whether you can replace them is another story, as the wee one pointed out above--