Just bought my Lumia 950XL on MS website when it became available on Monday afternoon. I was lucky that I saw that it was available because it sold out in four hours. MS never said how many it sold but I'll bet that many of the sales were to Verizon customers since we have had the poorest selection of Windows phones of all the major carriers.
I wonder what Verizon will do when these phones are delivered next week. I called Verizon and they said I will have to take it to a Verizon store and see if they can activate it. If not, Bye - bye. I have already checked the ATT plans and they are identical. They are selling the 950 which means the XL will work also.
I have been a Verizon customer for years and I can't believe they will just let the customers go. I have been running the WP 10 on my Lumia 822 ever since it was available and it is great.