samba - May 2015 - Working example of mount.cifs -o setuids

Hi.
How do I use the option 'setuids'?
Logic suggests that it's intended for root mounts (with the ability to
chown from client), but everal threads on this list say the opposite.

Anyway, I can't make it work with or without 'valid users = root' or
'admin users = foo' in smb.conf. I tried samba 3.6.9 and 4.2

Please can someone post a working example of smb.conf, mount command and
some test shell commands, with which the presence of 'setuids' would
make a differene?