nootanklebiter

1 core and about 5gb of ram for each server / grid is probably a good estimate.  I'm currently running a 3x3 on a single machine (2 cpus with 6 cores each, and 64gb of ram), and it's sitting at 70% CPU usage, and 70% memory usage (45gb ram being used).  

Try spreading your ports out farther.  I had mine spaced by 1 like yours, and was having issues as well.  I am now spacing them out by 5 (read that 2 was enough but I wanted to be sure), and I no longer disconnect when transferring servers.