Thanks tihero -

The game is in 4 hours - i just want to check with some of your reasoning -
I've had a better look at his line-up and it's extremely versatile. I watched his match last night (4-0 W) vs a 4-4-2 and he can completely alter it.

His DL/DR & DMC can play DC. So he can make a back 3 while watching.
His DML can play DL & DMC - his DMR can play DMC - so if he wanted he could drop to a DL-DC-DC-DR & DMC-DMC or DL-DC-DR-DMC-DMC-DMC.

His AMC is also an AML - and he has another AMC/AMR and AML/AMC on the bench. So he could switch to a 4-5-1V very easily.
As I see it - he has

----Option A-------------Option B--------------Option C--------------Option D---
--------GK-------- --------GK-------- --------GK-------- --------GK--------
DR-----DC-----DL ----DC-DC-DC---- DR--DC---DC--DL DR--DC---DC--DL
DMR--DMC---DML DMR--DMC---DML ---DMC----DMC--- DMR-----------DML
-----MC----MC---- -----MC----MC---- ----MC------MC---- ----MC------MC----
--------AMC------- --------AMC------- --------AMC------- --------AMC-------
---------ST-------- ---------ST-------- ---------ST-------- ---------ST--------

And with one substitution he can have a 4-5-1V or something to counter my counter.

The first formation you suggested -
---------GK------
---DC--DC--DC----
--------DMC------
--MR---MC----ML
---ST--ST--ST---

Would my MC & DMC pair not be outmatched by my opponents 2 MC & DMC - also with DL & DML + DR & DMR would that not make my ML & MR redundant?

Also it's not a good formation vs a 4-5-1v

The second formation might be better - But it's also weak against a 4-5-1V.