@Peter , @Rorepme ( and to a certain extent @Elizhaa)
I didn't know about these CQC Full Counter feats, fair enough (and thank you). However, (putting on pause Natsu's null magic some have brought up) I don't think it dispells my statements that, at CQC, Full Counter is a non-factor. First, I still don't imagine Mel FC most attacks in a heated CQC and his battle against Gil (chapter 6 & 7) you used as argument did little to contradict me (he doesn't FC half of Gil's attacks; only one). More importantly, by design, you can only CQC Full Counter what you could've dodged or guarded anyway (because it requires the same or more amount of movements than dodging).
The only advantage of Full Counter is inflicting x2 damage to the opponent. If (like against Natsu's fire resistance) the damage part is taken away, CQC Full Counter is nothing more than a guard or dodge with more wasteful and more restrictive movements. Saying he Full Counters (most of / all) Natsu's attacks is like saying he dodges them all. No, speed is equal. Natsu has also shown to guard and dodge attacks, yet no one is saying Natsu evading or blocking attacks is an important factor in a match. My second statement was CQC Full Counter may negate the Fire around the punch but the punch still needs to be blocked, evaded or taken in the face. Again looking at the (probably retconned?) Twigo stuff (look at both page 50 then 51), he dodges the attack and after uses Counter. Gil's case (look also at the next page), Counter is also used after the physical attack landed (it's ambiguous whether he dodged and endured the attack). By the way, Estarossa shows similar pattern of FCing evaded (or while evading) attacks (but that's a subject for another time).
To conclude: if the opponent resist the reflected damage, at best, CQC Full Counter is a more wasteful dodge, at worst, still requires you to dodge or take the hit. (though the truly worst case is the one 1997KD argued for)