I have the full complement of VC S-mount lenses, use them all and have never had a problem with the "build quality".
In your case I would keep the 50f1.4 and the 35f3.5 and add a wider lens. The 28f3.5 VC is difficult to find now, but you can also get the 25f4 in S-mount. IF you can "score" a VC 28f3.5 get it. It is one of the best 28's around, both in LTM and S mount. Just dedicate on body to it, with a finder and the other body will be your 35/50 body.
The 25f4 is very good, but if you are a black/white shooter - the 28f3.5 is quite extraordinary in its tonal rendition - and sharp too.