Let’s preface this by saying that we know that the Google Play Editions of the Samsung Galaxy S 4 and HTC One are not especially common in Australia, especially as they’re only sold in the United States.
However, a good number of people have converted their normal Galaxy S 4s and Ones into the Google Play Edition versions, simply because they like the hardware offered by Samsung and HTC respectively, but prefer a more AOSP experience on that premium hardware. Perfectly understandable, it’s something that one or two Ausdroid staff have done as well.
These brave folk who have gone through the conversion process (read: it’s not particularly easy) will be pleased to know that the Android 4.4 OTA updates are now available, and with a bit of tweaking, there’s a good chance you’ll get KitKat working on your devices fairly quickly. It’s important to note, though, that while you’ll get 95% of the experience seen on Nexus 5 devices, the Google Experience Launcher is not part of the update, so if it’s that you’re after, best go buy a Nexus 5 instead.