I just got this 16/1.4 "C" at a good price used, knowing full well it came without the original lens hood (LH716-01). With a bulbous front element, I knew that working without a lens hood would be problematic. Before shelling out $24 plus shipping for the hood, thought I'd get the lens first and see if anything I had fit.
In this case, I had two Nikon HB-32 hoods with a 67mm thread, original to the Nikkor 18-105 VR.
Did they work on the Siggy? You betcha. Not only did they work, they rotate and lock into position nicely. A check at the smallest aperture I'd be using in real life (f/8) showed no vignetting.
A very informal test between the Siggy 16/1.4 and the Oly 17/1.8 showed the Siggy ahead in resolution, but not by much. The Oly 17 is a splendid design for such a small package. The Siggy is three times bigger, but balances very nicely on my E-M1's and GH2; not so much on the smaller body Pens with the lesser grips.
I really like where Sigma is going these days. The 16/1.4 was originally designed for an APS-C sensor (Sony E-mount) and then reworked for m4/3. I might be looking at the Sigma 56/1.4 as well if the 16 proves as good as it seems.