What did they do at the repair center to fix your problem? Just curious. I have a couple of friends who own the 950 and both have this problem with the rebooting and some freezing.
I have two 950 XL's and neither of them have ANY of the problems that others have had. I had them approximately two months with no real issues. I have only had an issue with the sensitivity of the touch screen which appears to be due to the thickness of the glass screen protector I'm using. Apparently, there are different thicknesses depending on the brand. Other than that I have pretty much ZERO problems with the phone and it is working pretty much FLAWLESSLY.
But again, I'm using an XL that I purchased from a physical Microsoft Store and NOT from AT&T. I'm running the latest version of firmware/software .39005/10586.107 I'm also using a SanDisk Ultra 128gb card with EVERYTHING including apps being saved to the card.
Yes, I am a very happy 950 XL owner and daily driver user. I have also owned Lumia 830, 930, 1520, Samsung Ativ S Neo, and an HTC that had major issues. Every Lumia and even the Samsung Windows Phones have all been and continues to be AWESOME!!!! Apps are a minor issue for me. Since Chase dropped Windows Phone, I dropped Chase and went to Wells Fargo instead. So, now all is great!