I find the OSU models the most useful so far because the inverter is better balanced and the models are more detailed - presumably because they are layout extracted. The ring oscillator link above uses the particular design of the sky130 mux2i. I haven’t seen the OSU muxes which will likely use pass transistors so they may not be as useful for analog.

I am experimenting now with improving analog performance by changing the bulk biasing of the sky130 cells. I will report on that soon.