KAI has worked out two versions of the KFX-E, one with a single fin and one with two, the latter presumably demanding more development work but reducing radar reflections. KAI has not provided for a weapons bay in the KFX-E; ADD has reserved space for a bay in its designs, though neither the C103 nor C203 would initially have one. Following a 2009 decision to downgrade the stealthiness of the KF-X, the ADD proposed first to field an aircraft whose shape would give it the makings of a low-observable fighter. Later versions would introduce features to realize that potential.
Also much smaller than and more differentiated from the , the KFX-E may offer the further advantage of minimizing competition from that U.S. stealth fighter. But it may have or other U.S. intellectual property in its design, exposing it to a foreign veto over sales or even development.
As of 2006 KAI (Korea Aerospace Industries) was trying to push the NSC (National Security Council) to replace the KFX with an F-50 fighter version of T/A-50, but the ROKAF sought to continue the KF-X project. Korean Aerospace Industries (KAI) would have difficulty developing the KFX at the same time as it is focused on the production of the T-50.