Interesting feedback, and I for one appreciate your comments.
I've been a dedicated iOS user since my iPhone 3GS and MacBook, and I haven't ever considered jumping to Android. I had to swap my SIM card earlier this year, and while waiting at the AT&T store looked at the other offerings. I particularly liked the HTC One for the size (4.7") and build quality. So, I know for sure that I could live with a 4.7" iPhone. If Apple does indeed offer something bigger, I'll definitely get some hands-on with something of a similar size before committing.
Especially as you say that the Note 3 is too big for cargo pants or a large jacket pocket, a potential phablet-sized iOS device might end up being too big for me. I - like every one else - will just have to wait and see what Apple offers up come Fall, but I'm excited about the possibilities even if 4.7" is the biggest form factor.
I've owned every iPhone since the beginning, except the 4s (not enough of a step up for me) and 5s (the shortages stopped me from getting one whilst I was in the USA and I refuse to pay the equivalent of $75 more in the UK for the 16Gig than the 64Gig would cost in the States) and I currently have an iPhone 5, an HTC One and a Note 3. The Note 3 is just about big enough for cargo pants or a jacket, sorry if my statement was misleading. You do need very large pockets though, especially if you want to put a case on that!
The HTC One is about as perfect a screen size as it can get and if Apple produce a phone with a screen size approximate to that then I am sold. I hope they can fit it into a smaller body than the HTC One though if they reduce the size of the bezels.
The Note 3 is definitely too big and to be honest, Samsung just doesn't really do it for me. I went to the larger screen as I needed it for work but again, I would much rather use a larger screened iPhone as it 'just works' unlike my Samsung which requires factory resets every couple of months to iron out the glitches that seem to worm their way in with alarming regularity. The HTC has been perfect so far apart from the stupid curved back which makes typing whilst it is laying on a flat surface completely impossible. The HTC certainly feels way more premium than the Samsung but not as premium as the iPhone.
Personally, I am holding out for a circa 4.7" screen iPhone. If they release a larger device then I would still go for the 4.7" one unless they decided to put different and possibly slightly sub-optimal components in the smaller one, compared to the larger one.
Over on AndroidForums.com, where I also hang out (being both an iSheep and a Phandroid, I clearly argue with myself constantly) they love the Note 3 and for the most part people are extolling the virtues of the larger device.
So it really is horses for courses. As long as you have big pockets and can live with holding and using a device with a screen size of around 5.5" then you'll be fine.
Still, we don't yet know what Apple are planning exactly and all the speculation and rumours could be for naught (although as they say, there is no smoke without fire). You'll probably do what I will and check them both out in store before shelling out yor hard earned anyway.