Hi Dave,
Thinking of getting something like this myself, so handy to see the Sigma - the CA is better controlled than I was expecting, did you apply CS6 to deal with Chromatic Aberration (CA), or is this SOOC in that respect?
Focus and distant detail look OK to me viewed at 100% (click on image then hit "F" key) in Lytebox, but if viewed in thread, it does look soft, on #1 especially. Looks like you pushed the sharpening as far as you can.
As Manfred says, you seem to know the tricks of using an UWA.
As a processing 'thing', rather than a lens 'thing', I'd have boosted lowlight details a bit more in all three for my taste.
Enjoy,