If the M AF behaves anything like the contax then AF can be problematic. Yes, spot focus (C doesnt have) helps, but in general landscapes are better if you just focus at infinity, esp for blow ups.
All the AF have tp make assumptions; not necessarily what the photograpger wants.
I find the 35mm can be used if you do not have strong foreground contrasts otherwise, use manual and or infinity.
Having Leica's for many years I find MF MF easier. WHen I want to use AF check where the focus IS. I often get the focus, depress shutter halfway to trap and then recompose. Works for sport very well.
BTW, congrads on getting a good 28mm. For all the complaints and fuss, I see MFDB winning out over any DSLR for many applications, WA lanscape and interiors are two.