I tried to get this to work with an earlier version of MJ about a year or so ago (the idea of a centralized database where you only have to manage once - I have 5 pcs and a mac hooked up at home - is really cool.) I couldn't see my internal stuff let alone outside my network. (Although the MJ guys could..)
With 8 I've got it working perfectly internally and expect that once the NAT routing is set, it will work externally. DSL will be tough to get to work as the IP changes and you have to log in. With the router, the IP will still change which will screw you up. I'm on cable now, so the external (what the world sees) stays the same. All the NAT setting does is route any request from the outside world to the internal network IP address/port you specify..
I'm going to give it a try on Monday when I get to work... I'm not sure that I can get outside of work's security tho...
Mark