The big reason for wanting to use these cameras is that they have "electronic first shutter". What this means is that you can use them in a way that does not use a mechanical shutter in any way, thus avoiding camera vibration. Some literature calls this "silent shooting mode", but the point here is not avoiding noise, although noise is certainly an indication of vibration. More pixels is sort of a fringe benefit.
Using a Sony camera for macro work turns up a surprising number of shortcomings in the Sony system. Sony does not support tethered shooting (or more specifically Adobe Lightroom does not tether to Sony Cameras). There is no separate remote shutter connector (it all happens through the USB cable, which is also used for tethering). Dealing with these issues is inconvenient, but manageable.
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