This is my test to check if serial communication work:
I use 3 arduinos nano with MrlComm inside. I connect each of them on serial1, serial2 and serial3 on the mega left or right. I Connect one servo on all nano.
With MyRobotLab, I move 3 servo.
With MrlComm 55, After few minutes, MrlComm 55 break the communication, doesn't work.
With MrlComm 41, i have no problem, the test work all the time. This is called reliability.
So, moz4r, do this test and give your result !!