There's not a FreeBSD port at the moment, though there's been some noise about the developers creating one. As of now it stands as a Linux program for the server with a cross platform client for Windows/Mac/Linux. I'm sure it lacks some Milestone-esque features, but for what it does do, it does well. Motion detection is good, the control panel within the client is great, it exports as MKV which takes out the nonsensical proprietary formats that a lot of others still (astonishingly) use, etc. It lacks a dedicated mobile app, but I interfaced it with TinyCam Pro, which works great for live view. The developers have been awesome; spoke to them a few times already. It's also shockingly light. I have my 4 cams in full time record at the moment, but my system load is 0.01. I was running motion detect at one point, but even still, it surprised me at how low it ran on this 2nd gen low powered i3. And here I was expecting I'd have to get a mammoth i7...
There's a 30 day free trial that they encourage folks to spin up and see what you think.
Hey, to each their own, brother. All I'm saying is, having seen what sort of random issues that can come up with Windows, it's not a platform I would rely on for video surveillance. If it works great for you, more power to ya.