I have now had my 1520 for a few months short of 3 year and will be changing carriers when my contract finally runs out, I plan to buy my phone and go with the carrier my daughter works for with large data allowance for not many pennies (Staff discount).
So my choice is 950 or 950 XL, given my 1520 ownership I am leaning to the XL but if I went 950 I could always give that to my wife to replace her 830 when "Maybe" a Surface phone appears some time in the future, but I doubt she would want an XL, so if I went the XL I would probably have it for at least 18 months/2years.
I like the idea of dual sim (Handy but not vital) and I like the idea of actually being able to surf the web with ease instead of fighting the screen (It's not been as bad as some have reported but you could notice it), I really like the idea of Continuum, and my plan is to go to just three devices, desktop, Surface Pro 3 and the phone, so ditching my Stream 7 and making more use of the phone.
So good to read some people like them, I am enjoying 10 on my 1520 so I shouldn't think I would see it working worst on a new phone.
Any opinions 950 v 950XL, as mentioned I do have a couple of months yet contract wise, but I can afford to buy the phone when I want