Given that it's a Voigtländer I am assuming that center sharpness & build quality are admirable
Exactly.
I did a few tests today.
What I can say already is that sharpness is
very good.
I had no metering problems at all with the lens.
I will present some results tomorrow.
I don't have a DA21 anymore, but a Sigma 20/1.8.
A while ago I tested the Sigma against the DA21 and the Sigma was better in all aspects, except size.

So I will give some comparison with the Sigma.