Here's an idea:
How about not implementing things like Ixion in the first place?
You...
1). Implemented something you knew would be in extremely high demand such as a unique mount on a FATE.
2). Made said FATE spawn only once per few days.
3). Made it so that you must clear this FATE 6-12 times.
4). Stuck this FATE in the highest level zone in the game currently, the very same zone that contains the last bits of the MSQ.
May I ask you a question?
What were you thinking was going to happen as a result?
It almost seems like you did this and then a collective gasp was heard from the development team when the obvious happened and now you're scrambling trying to find ways to "deal with the congestion".
The easiest way to deal with a problem, is to avoid it in the first place. Since you know large-scale ultra-rare FATEs that have extremely popular items will cause this sort of thing... how about not doing it in the first place? Or perhaps add some randomness to it instead of allowing it to follow predictable patterns so that everybody knows exactly when and where this FATE will pop so they can all go rushing to the zone when it is due to pop?
And why 6-12 times for the mount? Once isn't enough? It's a mount. If you wanted to make it harder to get, you could have stuck it in some type of instanced content as a rare drop or something instead. You didn't have to absolutely destroy a whole area for roughly an hour time slot and then be forced to add Instances back in.
I'm really scratching my head here, trying to understand just how this even happened in the first place. Did no one predict this during the design phase? During QA?
It is also my understanding that this is not the first time it has happened. Did we not learn from the last time, or something? I don't want to sound like I am disrespectful of SE or its employees, but I feel these are legitimate questions that really should be answered.