A few first samples shot casually and processed to taste with the Sigma wonder software:
I would agree that DR isn't as good as the best DSLR such as the D810. This isn't helped by the Sigma sofware that doesn't offer the possibility to control extreme highlight and shadow recovery independantly. The Fill light function affects both ends.
This is also definitely a base ISO camera. I am not comfortable using it above ISO400, and even that is a bit of a stretch. Staying at ISO200 and below is best.
The sharpness, micro detail and colors are great though.
Cheers,
Bernard