Rooting is still a controversial topic among Android enthusiasts. Bring it up, and be prepared to hear countless arguments for and against it. One one hand, root opens up a world of possibilities, but on the other hand it's not often that one needs to take advantage of the cool things it enables.
However, we can all agree that what's most important is having the option to choose. And if you plan on getting a Samsung Galaxy S6 or Galaxy S6 Edge on launch day, then you should know that rooting its Android distribution will be possible right from the start.
Root for Galaxy S6 and Galaxy S6 Edge is made by possible by the CF-Auto-Root tool, developed by renowned Android modder and developer Chainfire. It has been tested on an actual device, so it is verified to work in real-world conditions.
I should point out that we are not talking about a rooting tool that covers all possible Galaxy S6 and Galaxy S6 Edge versions, but rather one that supports versions of the two smartphones which feature an unlockable bootloader. That mainly includes the unlocked versions of Galaxy S6 and Galaxy S6 (not carrier-specific versions) - or, at least in theory, as the tool is even more focused at the moment.
The first - and only - recipients in the family to receive rooting capabilities are the T-Mobile branded Galaxy S6 and Galaxy S6 Edge, which feature the model number SM-G920T and SM-G925T, respectively (software build number LRX22G.G920TUVU1AOC9 and LRX22G.G925TUVU1AOC3, respectively). Others will surely follow, as Chainfire gets his hands on the files he needs to assess root potential.
As always, there is a risk one has to assume before rooting Android. In this case, Chainfire points out that it is possible for root to be flagged by KNOX (Samsung's BYOD-friendly, security-focused software included with its Android distributions) and as such, mobile payments - specifically, Samsung Pay - to be taken out of the equation.
My advice is to steer clear of root for Galaxy S6 and Galaxy S6 Edge, until you get the full picture post-launch.