Well, my blue Pyrus Mini arrived this afternoon and I have to say I'm fairly pleased. The display is nice, sharp and clear, although the buttons are a bit hit-and-miss. I expect this to improve as they are used for a while.
I have loaded up some Orwell and shall read over the next few days and report back on the usability and stability of the device.
One small wrinkle I have experienced is that Calibre does not recognise the Pyrus, although I suspect that this is due to it not reporting its device type. A future update can address this.