Hmm... I'll be a bore again, but I'm afraid I'm not done with autofs. I had only checked browsing through the folder structure. Only when I needed to copy files for real, I noticed that the copy failed because of permission denied. As if the autofs-mounted folders were read-only. Yet, it's definitely "rw" in my auto.sambashares file.
OTTH, if I "browse network" from the file manager, I see the same shares, the very same directory structure, but I can write to them.
So I'm thinking of permissions problem. I looked at them, comparing both cases. The shares are owned by root. But in the 1st case (autofs) the access is read-only, whereas in the 2nd it's read-write.
I tried to make myself the owner of a share, grant r+w rights, but I still can't get that to work