no upgrade path at the moment… while @mark_nl is busy, i’m testing ns7 final on rpi…
if someone what to help me, are really welcome 
is only a test, probably not so stable so, be careful
create the sd with centos 7-1611 as per wiki
http://wiki.nethserver.org/doku.php?id=ns_raspi2
then set your keyboard, ie:
localectl set-keymap de
and expand root partition:
/usr/local/bin/rootfs-expand
update:
yum clean all
yum update -y
install ns7
yum localinstall http://mirror.framassa.org/nethserver7-arm/nethserver-release-7arm.rpm
nethserver-install
please report back, and please have patience, i really am short on time 
tested only on rpi2 (i’ve left in the repo the aarch64 files but i didn’t have hardware to test)
tnx