Dynaudio Consequence UE

What is your opinion on the placement of ultra high-frequency tweeter units (like Elac 4 Pi) on top of Consequence UE?
Yes, as stated you really need to hear this statement product....don't let your eyes deceive you based on the driver arrangement as your ears will certainly be pleased....
I have a different take, I think you should try it.

I have owned many Dynaudio speakers including the "baby" Consequence, Confidence 5. I loved the sound, but I do think Dynaudio can use more air and extension.

I have also heard Elac with 4 Pi tweeter and I have to say it's one of the very best out there, rivaling (if not better than) MBL 101E. I think you will find a pleasant surprise how much better the 4 Pi can add to any good speakers, Elac is much more popular outside of US and very commonly added to high end speakers.
Sounds like you have an affiliation with Elac. Air and extension are not a problem with Dynaudio,what you won't find with Dynaudio is any coloration or un natural emphasis on the high frequencies.

Sounds like you think Dynaudio is the most neutral speaker on earth?

I am not sure about that, I have owned enough speakers to know...