samba - Jan 2013 - samba 4 dc, shares without ACLS and group permission bug?

Hi,

ACLS are a pain in general. Fortunately we do not need it for our shares, so I
thought to just add the following to my share definition in smb.conf.

nt acl support = no

This should be fine, isn't it?

Further I only need access permissions per share but I realized that the group
permissions won't work:

valid users = @Domain Users

but per user it work well, eg.

valid users = demo01


Would be nice if somebody could clarify my issues.