I am looking for blogposts, tutorials and reviews of KDE on alternative platforms like OSX and Windows.

I mostly used open platforms like Linux, Haiku, and FreeBSD but since I will be facing users with Windows and OSX experience I would like to know the status, process and what to expect in KDE for their platforms.

Please let me know how and where to gather this information.

Well, there are forums here for KDE on specific OSs.
Both Windows and OSX have dedicated websites at windows.kde.org and community.kde.org/Mac, and mailing lists at https://mail.kde.org/mailman/listinfo/kde-windows and https://mail.kde.org/mailman/listinfo/kde-mac.
Reviews for KDE on alternate platforms have been pretty sparse, and since stability changes pretty dramatically between releases your best bet is to try it yourself and see what you think of it. I have used KDE on Windows for a couple of years and things tended to work ok, depending on which version you were using, but I haven't used 4.7 so I can't say anything about its stability on that platform.

Try it myself? I am not touching no stinky Proprietary OS. Which was my point on starting this discussion so people that have can voice their rants and raves.