the studio4 works in tandem with the unitor 8 + amt?
im assuming the unitor 8 + amt are linked.. and the studio4 is not?
u can only link two of them at once when using an opcode/mtp 
but with emagic amt/unitor8 u can link many more isnt that true?
I´ll try to explain:
the studio4 works in tandem with the unitor 8 + amt?  -->  Yes, the 4 racks (2 emagics + 2 studio4) works together, as long as the Opcode OMS Studio Setup recognizes the emagics if the driver for them are present in the system, so that gives a total 32 independent MIDI lines, 16 channels each of them, a total bunch of MIDI channels.
im assuming the unitor 8 + amt are linked.. and the studio4 is not?  -->  As said, you control 4 racks within OMS   
u can only link two of them at once when using an opcode/mtp  but with emagic amt/unitor8 u can link many more isnt that true?   --> With a single SERIAL port (that is my actual setup, with the JAMPORT mod installed), you can use only 2 Opcode Studio 4.  I "only" have 2 USB emagic, but manual says that you can link up to 8 racks, connected to a single USB port at the MAC.