Hello SMeK,
I own both lenses you mentioned, and in my opinion, yes, the DA35 is sharper, and has very fast AF. It is one of my favorite walk-around and street lenses. The I.Q. and color rendition are superb. It does benefit from a lens hood to avoid glare and flare, also to prevent damage; the front element is close to the filter ring.
You might want to check your catalogue of photos taken with the 16-45mm to see if the 35mm focal length is one you use the most. Before I bought the 35mm, I was suprised to find it was (roughly) my second-most used length on the 16-45mm. In first place was 22-25mm. So I also bought a used Miranda 24mm f/2.8, auto aperture but manual focus. About $100.00 USD, a good deal on a fine lens.
https://www.pentaxforums.com/forums/lens-sample-photo-archive/204205-miranda-...-mc-macro.html
Now I take the 24, 35 and a fast fifty, hardly use the 16-45mm much anymore!
Have you seen the "Plastic Fantastic" thread? Lots of good examples there.
https://www.pentaxforums.com/forums/lens-clubs/196639-da35-f2-4-plastic-fantastic-club.html
JMO,
Ron