I worry re the X how it comes out in November (if you are lucky as supply will be tight). I think over next year they will ramp up the OLED supply and next year be back to the September release cycle, so will only be latest phone for 9 months before being replaced - kinda like the iPad 3.
I was also thinking of joining the upgrade program, I I don’t want to be on that starting in November as in future years I will always have to wait a couple of months after device is launched to upgrade (you need 12mths of payments) I think that next years version of the X will have any issues ironed out and better face ID etc, Apple might even have figured out how to have touch ID under the screen.
When looking at a comparison, the spec difference between 8 and X is not much, apart from form factor/screen and a few minor differences, i.e. animoji which I personally wouldn’t use.
So thinking of passing my 7 to my wife (retiring her 6) and then getting the iPhone 8+. Note to me its not about the money, I can afford either.