I thought I'd give a general update, as I've had my 49x900e for a couple of weeks now.
So far, I love, love the set. I really couldn't be happier with its performance to this point. It fit right in where I had hoped from a dimensions standpoint, and I didn't need to do any extra work other than remove the old TV from the mount and put the 900e in its place. (Thank you VESA for that.) It works great with my Sony CT390 sound bar, which for some reason didn't seem to perform as well with the older TV, but does really well now. I also didn't realize I'd get 5 free 4k movies with the set via Google play, but that was a nice bonus. It was a limited selection, but I was overall happy with what I got. (Spiderman Homecoming, Close Encounters of the Third Kind, Baby Driver, Ghostbusters , and Jumanji [the older one.] I actually realized I don't think I EVER saw all of Close Encounters - what a great movie!)
I also went ahead and got my Harmony Smart Hub and remote set up that I had bought in anticipation of getting a new TV. Now my Cable Box, FireTV and other stuff are all tucked away and the remote does everything I'd want. (I had an older Harmony 650, but this remote is MUCH better with its BT and non-ir reliant capabilities.)
As far as what I've watched 4k wise thus far, I really love Planet Earth II on Netflix. It's one of the best things I've found that really showcases the new format. Spiderman looked great in 4k, as did my The Force Awakens BluRay even though that was only upscaled. I do have a few 4k discs, and have an Xbox One X on the way to take advantage of those. (Coco, The Last Jedi, The Martian.) I also hope to soon watch one of the Netflix shows that is in HDR, but I haven't gotten to that yet.
Thanks for all the help in this thread, I'm very happy I ended up here.