I am not trying to be provocative here. I know a few people that got the 8 Plus yesterday going big and upgrading from regular 6. They asked my advice first and didn't take it.
The screen of the X is bigger than the plus and the body is pretty much the same as the regular 6/7/8. Not to mention new technologies that will surely become a staple of the product line.
I understand the material price difference of the 8 vs the X, but the 8 plus vs the X seems close enough and compelling to wait a month and get state of the art hardware vs an almost four year old form factor.
-Some people care about $200, or whatever. In my case, I don't see the value in a phone costing that much. This is more prudent since I would get the 256gb, plus apple care, tax...$~1400 phone. I can buy the iPhone X outright, or I can pay for it monthly. But by getting the iPhone 8 Plus, i save $400 buck/20 bucks a month about. That is a nice trip to the Canadian wineries up North, or a night out at a sports bar once a month. The point is...everyone views technology differently, and some people are not ruled by having the latest and greatest.
-The screen is bigger, but skinnier. The surface area is similar. Put an iPhone plus next to a galaxy s8. The s8 has the larger diagonal screen, but the screen is noticeable smaller. I guarantee people will be arguing, come November, about which aspect ratio is best. Y
-It isn't one month of waiting. If the supply vs demand is as bad as they say, then most people will be in a long wait. Everyone says "get in the first 60 seconds", which works...unless the Apple store lags/crashes. You could be waiting 1,2,3+ months. If you wait 3 months, then you will be 3 months closer to the next iPhones (this matters if you upgrade yearly on apples program or your carrier program).
-Some people want a finger print scanner. I am one of those people.
*I am really enjoying the iPhone 8 plus. OLED is the future, I have had several phones with that tech. But, after about an hour, I get used to the display. The TruTone LCD is really nice. Anyway, next year, the form factor/tech/etc will be optimized into a better product. It happens every time. I'll wait and see what happens. But I guarantee Ill be just as happy with my phone, as you are with you X.