I have been using 8.1 on my main render machine, plus the Win10 review on another. There are definitely some better 64-bit multi-core memory management things in newer Windows, which helps large-memory tasks like Poser. As for trust ... I think you either need to "trust" Microsoft, or start using Ubuntu Linux and blender. If you don't trust Win10, then how would Win7 or XP be any better? Your either on the bus, or off it.

(I have an 8-core 4.0 Ghz AMD with 16MB and 256GB SSD for Windows, 3 TB for Poser content, PPro2014 and Win 8.1)