I am 99% finished with the Preto Sans and Preto Serif family. Now I am working on Preto Semi.
It is an experimental text type, where I am working with serif, changing their function and trying to create a "better sans with some contrast". The serif is placed on the position, where it is logical to fill empty spaces (making the color of the text more even), or when the thin lines need serif to balance contrast, or serifs are placed on end strokes.
Look at the pdf in the attachment.
What do you think of it?