A friend of mine has a collection of old Pentax lenses from her father. She was so friendly to let me try the 28mm f3.5. Fully manual, not the M series, but the K-series.
As I am from the film era, I'm used to work with manual lenses. One of the biggest disadvantages is the aperture not working with the metering system. Or it meters full open, or I have to push the green button to meter before shooting.
I think an A lens would be more convenient, or I have to get used to it, or shoot full open.