I want to know what required to tune a dual drive (servo motor) system for a U frame 4x8 table... whats needed to done what are the steps etc...
whats the pro and cons vs steppers setup?

see attached pic

I am not sure whether you can use dual servo drive unless the loop is closed in the controller such as Galil etc, where you can use electronic gearing.
one motor is slaved off the masters encoder, although the slave does still have an encoder also, with this system you can even change the 'gear ratio' to whatever you wish .
Systems that use steppers can do it because the motors are synched by the identical stepper pulses.
Al.