Reference Modeling

I would like to work on my low poly cube-cage while i see the results on a reference copy sitting next to it, with smooth subdivide mod active (i did the reference copy with alt-d)

the problem is:
the change i do in edit mode on my low poly cage original is only then transfered to the smoothed reference whenever i exit edit mode and not simultaniously in “realtime”.

->without a sub-mod on the reference, the original and the reference copy are perfectly linked in edit mode though.

i am very used to this way of modeling from max and i know i am not the only one:
http://blenderartists.org/forum/archive/index.php/t-29181.html

Any ideas on that?
An addon maybe or an alternative version of the reference copy command fitting my needs?

thx