I think as long as someone gives consent to use the Echo, doesn't try going about telling everyone by blabbing about the hidden group, and doesn't try to act out every piece of the main storyline, I just might accept the whole use of the Echo. For example, no doubt in the way the FF stories usually go, our characters will most likely somehow save Eorzea from a grim fate. That said, not everyone can suddenly be the "hero" of the day and save the lands. In fact if someone even tries this my character will downright look at them as if they're nuts. If you try to forcefully do something using the Echo without my consent (IE read something that was written OOC and suddenly bring this up ICly without any way of knowing outside of Echo use.) I will flat out blist you on the spot and just pretend your character had a mental breakdown right there, whatever amuses me.
Quite honestly I'm strongly against the use of the Echo, even if it can be tweaked with a little use, as according to the storyline, none are supposed to even be aware of this ability, or even speak of it. And in fact, as the storyline goes... Should you be found out, expect others to either want to kill you, have you exiled, thrown in jail and locked away, or utterly shunned. From what I can see, I don't believe it actually alters a history or what happened, but the person you used the Echo on just may realize you're not actually a part of that should you be seen in the memory. At that time, the person on the outside, will suddenly become aware you pulled some sort of strange ability and invaded their thoughts. So be careful, be VERY careful using this and either be prepared to be the victim of possible death threats IC, or hated ICly by many.
Quite honestly I'm strongly against the use of the Echo, even if it can be tweaked with a little use, as according to the storyline, none are supposed to even be aware of this ability, or even speak of it. And in fact, as the storyline goes... Should you be found out, expect others to either want to kill you, have you exiled, thrown in jail and locked away, or utterly shunned. From what I can see, I don't believe it actually alters a history or what happened, but the person you used the Echo on just may realize you're not actually a part of that should you be seen in the memory. At that time, the person on the outside, will suddenly become aware you pulled some sort of strange ability and invaded their thoughts. So be careful, be VERY careful using this and either be prepared to be the victim of possible death threats IC, or hated ICly by many.