That is not correct, you don’t have to purchase E-Cycles, that’s a custom build BliBluBli is doing, he does some experiments, implement some features and optimizations and he updates it, after some time he wants to share his patches with anyone, but you can implement the patches yourself if they are already public.
Bear in mind that some of the features present in E-Cycles have not been reviewed by Core Developers, hence they don’t know if those are stable or not, in other cases, like with Dithered Sobol or Scrambling Distance, they simply did not have time to review and implement it in master, they will after 2.80 but not right now,they are working on stability.
Also, Intel Denoiser is completely new, not 100% stable and uses, for the time being, a lot of memory, we use it and we love it, and we hope to see it in master ASAP, but if they are working in 2.80 stability they cannot implement it either.
Theory Studios is doing builds, based on 2.79 because is what they use, but you can ask someone, or you can implement those things by yourself if you want them before they are in master, remember that 2.80 is beta, and the latest official release of Blender was 2.79b, that is really behind 2.79 daily builds in many things.
Even BliBluBli has a course to teach you how to modify C++ code and how to implement new features, he even keeps updating the course, I have it and it is pretty neat!
So don’t think you have to pay 100$ to get those features, they are public patches and you can implement them.
Also you can go to the new graphicall and you will find I myself uploaded a pair of Theory Studios builds, for Windows and Linux, with Scramble Distance, Dithered Sobold and Intel Denoiser, they are not updated to today’s master, but we use them to work.
Core devs are now focused on removing bugs and bringing stability to make the 2.80 release, not to add new features, we will see new features after release and when they com back to the 3/4 months release cycles for 2.8x.
EDIT: BTW, don’t get me wrong, I’m not saying that you don’t have or have to purchase E-Cycles, you can purchase it to support BliBluBli and his work if you want, he is doing some great things with different experiments and improvements, or to use those new experimental features, it’s just that I want you to be aware that you don’t have to purchase anything in a mandatory way to get new features and improved performance, there are other builds out there that are also experimental and optimized