IDM should not be confused with a proper data-link. It can be a useful adjunct, for viideo and such, but it cannot achieve what JTIDS can and does on a regular basis. The Jag community think its the bees knees, but then they've never seen the real thing. Thats so true of many things, like engines, too.
I'm told that size is unimportant, but nevertheless, most JTIDS terminals are considerably smaller, but just as capable, than the F3 terminal. As for integration, the F3 is recognised by the JU community as a well integrated solution, better than most.