The only thing, mission-makers would have to keep in mind, when building a FC X + DCS XY mission, is that the DCS guys would need a certain time to perform certain things (programming CMS/DSMS, Startup, working the CDU, etc.). In return a DCS A-10C would be so much more effective than a FC A-10A.
MP-Compatibility could be fun, as long as you have a fairly talented mission-builder.
But the guys that said "I don't want to read hundreds of pages thick manuals to get to flight and combat" do have a point. FC offers a fair choice of aircraft which you can get going with way less effort than a DCS aircraft demands. You can't compare the arcade-mode of DCS with FC!