Just remember where these stories are coming from. Financial analysts who have an agenda other than reporting the truth. They work for their clients ... and not the one's that the original post indicated the research note was sent out to. Their real clients are the big money fund managers that need the stock price driven in one direction or another.
The analysts can say pretty much anything they want because ...
a. they are not held accountable to incorrect "research" or inaccurate "predictions".
b. no one remembers anyway.
c. Apple hardly ever comments to refute these "reports" directly.
d. after the quarter closes, Apple is forbidden to release material information until the financial report comes out.
So these guys have a good 3 weeks to come out and drive the price down. They just want to get in at a lower price before Apple reveals earnings and then they sell. It's the opposite of the pump and dump.
Anyways, believe whatever you want. Apple won't tell you how many iPhoneX were sold anyway. They'll give a number for total iPhones sold and the total revenue. From there, you can do some math estimate the mix for the quarter.
If the ASP is in the $725 range,
that would indicate to me that the mix would be about 50/50 for the 8/8+ vs. X, but then that's even a wild guess. I'll have to put together a spreadsheet to analyze. see below
The higher the ASP, the more X's sold.
EDIT - I just did a quick spreadsheet using data showing iPhone product mix from CIRP
https://www.ped30.com/2017/12/27/apple-cirp-iphone-x/
CIRP is indcating a 29:38 ratio of X vs. 8/8+, plus a bunch of other models in there too.
Assuming a 70/30 mix of LowRAM/HighRAM within a model, I get an ASP of $786. I'm using US prices and I lumped in all 6S/6S plus at $449.
Now I'm really interested in what they report the ASP at.