Really nice to see this discussion being addressed more openly now. 3DGS isn't a bad game engine, every engine has it's strong points and other things it may not be so powerful with. I think the end result of all the bashing people for asking questions about the network layer simply closes the community to more powerful solutions. I am still very very surprised that no one has finished a C++ addon for 3DGS that contains a good networking library. I was very dissappointed to read that Wolf never finished the one he was working on. For all you people wanting to use 3DGS for an MMO (Even a small scale one) get yourself a good networking library. C-script is great and with a powerful network library addon you will be set

A couple of words for you from a guy who has "been dere dun dat" though. Trust me when I tell you that the network/server part of your MMO and connectivity is really not your biggest worry. I think if you ask anyone involved in large scale multiplayer developments the #1 thing they will all agree on is the complexity of the database querry system and dataflow. Your datastream is king in any many player environment and if you arent a guru at some form of database development you need to get in good with someone who is.
I wrote and re-wrote my data layer for my project well over 3-4 times and I think I got off lucky at that. Having a mySQL backend was easy enough but writing a scaleable datastream that had at the very least at least the potential to support 500-1000 players... Yeah.. that takes some doing.
MMOs are a mean animal. Everyone is an armchair expert and has a million opinions on this or that but when push comes to shove very few people actually get off their duff and get past the whole "theory" part of it and make things happen. Some exceptions to that? "A tale in the desert", "Minions of Mirth", several Korean based MMOs that I am personally aware of.. All these done by indies who had drive and clarity of vision.
For any aspiring MMO developers out there here is some food for thought. Josh wrote "Minions of Mirth" from scratch in 11 months.. He is somewhat of a programming dynamo but really it was his ability to understand all of the different components of the MMO layers and bring them together quickly and effectively. If you ever get a chance to hear him speak at a GDC definitely listen in.
Onwards my friends to bigger and better things
Good luck.