The sales breakdown has no relationship to demand that can be measured. The 6 plus is much harder to get. We have no idea how many people came in for a 6 plus, couldn't get one, so they bought a 6 instead.
I have. The experience is pretty bad. The nib is still really fat compared to a 'proper' Wacom stylus, it's battery powered (WTF?), and because the pen tracking built in to the pen instead of the screen, it depends on each app developer to support it. Very few apps support pressure sensitivity, and even fewer have palm rejection. When the digitizer is built in to the screen, stylus support and palm rejection is universal system wide.
As an artist who uses Wacom tablets every day, I was very seriously considering one because of the stylus. In the end I just couldn't stomach the thought of having to use Android, but I sure wish Apple made some products (OS X or iOS) that use a pressure sensitive stylus for drawing.
Bans for having multiple registrations is pretty standard. Some sites are so militant about this, that the only thing they check is the IP -- meaning two people in the same household can't even have accounts on the same site.
My 128GB 6 Plus did act erratically when I first got it. Rather than taking it to Apple, or complaining on a forum, I decided to do some basic troubleshooting. When I bought it, I set it up over the air from an iCloud backup, so the first thing I checked was to see if the problems stemmed from that. I erased the phone and set it up as a new device while physically plugged in to my iTunes library on my Mac. That went without a hitch, and I haven't had any problems since.