dmz on most domestic routers forwards everything to that ip. Never a good idea opens up ftp, ssh, telnet etc etc
should never be done and only done when the uneducated thinks it will make it work. It will work but opens up a security nightmare. I don't like port forwarding much less dmz.
not wanting to presume you have a marketing thing going on, btw I got your mail without the sae you promised.
Its a very very bad idea to put any bit of gear in the dmz of most routers.
Peter hits the nail.
Do you really want to recommend 2 with sleeping on site?
I know you have said your gonna stick with 4 but in some cases it may warrant more than.