But that's where we differ...slightly cumbersome is too cumbersome. I want not cubmersome at all.
You have every right to feel slightly cumbersome is too cumbersome. So if Apple goes with a larger screen device, I fully expect you to call them out on the egregious mistake of making it "too cumbersome" to use now. I take it from your post that you're implying that's unacceptable, correct? Will you not get future iPhones if they remain larger? I take your word for it.
Here's what I predict will actually happen (this isn't necessarily directed at you, ApplefanDrew):
Come October, give Apple the chance to explain why they've gone with a larger screen, and only then will the 3.5-ers realize the benefits, and also realize how capable they are to handle it with one hand and/or fit it into their pockets after all.