AETHERPHON, global theremin family

Hi people!

AS I am asking everywhere else, I am looking for any pedal/group of pedals 
to achieve the effect of "constant decaying layers" Pamelia uses. I know She 
uses a DL4, but there must be better choices at the market.

TO explain what I am looking for, look this video of the violinist Ed 
Alleyne Johnson:

http://www.youtube.com/watch?v=2fHOwTp0gXs

Anyone here knows any delay/looper unit able to make this effect?
I mean, with enough seconds ver loop to play a melody and harmonize it.

Thanks guys!

\ufffdscar