Well I received and installed my 1TB 850 EVO. Here are my first impressions:
The software that Samsung provides is FANTASTIC. It includes 1 program to clone your existing hard drive over to the new SSD (Windows and settings and programs and everything) and then another program to see anything that could prevent your SSD from not performing as it should. Both are AMAZING and simple and saved me a lot of time and headache.
Right away my PC was much snappier. Issues I ran into were that I did not start the new install the new SSD in AHCI mode, and I did not plug it into a SATA 3 slot and did not have it set up for RAPID mode. [EDIT] Research seems to indicate that RAPID mode is not really worth it and may cause instability, so I am going to turn it off when I get home.
Once I resolved all those the SSD was performing as per specs and the difference was even greater. Now the plan is to install Windows 10.
Additional Notes: I feel no need to get a drive that is any faster than this, this is easily faster than I or most people really need. probably for many years. So I am glad that I did not spend extra for the 850 Pro (so long as this one ends up being reliable). Or one of the $1000 PCIe NVMe drives.
Conclusion, buy a drive that is reliable first, then cheapest, as speed has become pretty irrelevant for at least the next few years.