To clarify on DragonMMC :
On the Dragon (or DraCo in Dragon mode).
Load Dragon basic file however you want to load it (From real tape, cas file, disk file etc).
Convert from Dragon to CoCo Tokens :
Save the converted basic program direct to the SD card :
The move the DragonMMC board into the CoCo (or switch to CoCo mode on the DraCo).
To load the CoCo basic program into the CoCo.
You may now save it to the destination format that you want e.g. diskfile, cas file or real tape**.
You can of course do the reverse to go from CoCo to Dragon, just using MRETOKD.
**I believe you should be able to save to a cas or a real tape without switching modes, as once the program has been retokenized, writing it to tape will make a tape suitable for a CoCo as the physical format on tape is identical.
For the discussion of all hardware related topics.