I have a similar unbranded lens that's f1.6. With the 2.5K crop mode, it's almost perfectly usable throughout the range. It's a fun little lens, and very versatile. The only downsides are the rotating filter threads, slight vignette at certain focal lengths, the zooming mechanisms/runners showing up in bokeh when shooting wide open, and spikey party-favor bokeh when closed down. So, there are some compromises.
I was looking around the ZLKC storefront on AliExpress and there are lots of neat 1.1" c-mount lenses on offer. I would imagine that they would cover S16, but I can't find any reviews.
Have you installed Crop Mood yet? The M becomes a whole new camera.
Ah, yes. I remember that mod. It was one of my favorite threads on this site. Once you start getting into 1/2" lenses and smaller, it really is uncharted territory. Too bad there aren't many interchangeable lens cameras that can work with them.