If Apple kill off the phablet, I'll be off to android. The 6+ is the most useful thing Apple have made in recent years.
It's pocketable, albeit a bit bendy, yet sizeable enough to be a car GPS, book reader, web browser etc as well as a phone. I'd even be prepared to go to 5.7inch, but probably not larger. It's totally replaced my iPad which I never really liked, too big, bulky and goofy looking.
The 5.5 starts to feel smaller every day. So I'm sure I could get used to a 5.7.
That said, the gf does what I do on her 4.7 and seems to love it even though I find it a tad small for many hours consecutive use. She seems to have no problem though and it is significantly lighter too, a hugely attractive feature for travellers, outdoorsy folk.