Can you use these 3DR Radios as just a generic pass through of information?

How tightly are they linked to the MAVLink Protocol used by theMission Planner and APM2 firmware?

From looking over the Wiki Pages it seems the only parameter settings that are specific to those components are the Mavlink Parameter that facilitates Mavlink message framing, and the injection of MAVLink 'RADIO' status packets that contain signal strength indicators as well as error rates, and buffer usage. Other than that, are there any dependencies?

I would like to use these as Radios as simply a wireless transport of a UART conversation. But, maybe I'm all wet and the radio firmware is tightly coupled to the expected formats of the protocol.

As a side note, the Wiki has a "S7: OPPRESEND=1" parameter. But the meaning of OPPRESEND was never explained.