So, many people keep wondering why use SUA vs Cygwin?
Well, first off the basic thing is speed. SUA has kernel hooks for syscall translation. It's able to do many of the POSIX syscalls in a much quicker fashion than Cygwin. Cygwin, on the other hand, does *everything* for POSIX syscalls in userland, causing it to be slow (for example, a fork, at times can take *seconds* to complete).
So, SUA is much better this way... problem is, it's tricky to get things to compile for it, I never did get things building reliably for it. Cygwin has a full suite of programs already built, and it's much easier to build existing Linux/UNIX/POSIX programs for than SUA.
Being a Windows user who needs *NIX tools for many processing tasks, what do I use? Cygwin. Easier to set up and get running. The speed drives me insane, though. My login script, which runs many programs before bringing up my bash prompt will take 5-6 seconds.
Ideal solution: Hyper-V or some other VM software running a VM in the background that I can get a terminal to, that has filesystem access to my system drives too.