xdm service deps on netmount but not nfsmount: $ grep netmount /etc/init.d/* /etc/init.d/xdm: after bootmisc consolefont modules netmount this means that things don't work well if nfs-mounted home directories are used.
It seems this issue is no longer relevant. nfsmount is just a dummy script that calls in nfsclient, however nfsclient is also called via netmount, the `after netmount` covers in this regard nfs.