Question:  Can I sub in Config-1 and MTX-A8 / MVX-A8 cards from a Com72 or System 200 frame into a Micromatrix frame?
Answer:  No, the config and port cards on a Micromatrix frame are unique to that small frame only due to the power supply utilized by the micromatrix frame. 
Micromatrix frames
The small MMX frame uses a filtered power supply brick that supplies +12 Vdc, -12 Vdc and +5V digital voltage to all the cards in the micromatrix frame.  On the cards for this frame the regulator and power supply filtering components are removed for the digital power supply and the +5V digital supply comes in to the cards on different pins of the rear edge connector. 
+12Vdc analog on edge connector pin 31
-12Vdc analog on edge connector pin 29
 +5Vdc digital on edge connector pins 26 & 27
The card designations are different, they are listed an "M" designation:
Config-1M
MTX-A8M
MVX-A8M
MTX-D8M

COM72 and System 200 Frames
The larger frames have removable power supply module installed that provides +15Vdc and -15Vdc analog voltage and a separate digital power supply module that supplies +15Vdc to the config-1 and MTX-A8 / MVX-A8 cards.  Because the digital power supply unit supplies +15Vdc it is down converted on the cards to +5Vdc via on board regulators and filtering components which make the cards incompatible with the micromatrix size frames. 
+15Vdc analog on edge connector pin 31
-15Vdc analog on edge connector pin 29
+15Vdc digital on edge connector pins 2 & 3