When I discussed this with their rep a few years back, I was told that they now believe that bi-wiring leads to phase distortion. Whether this is in fact correct, I do not know...BUT I certainly do NOT have that issue with my bi-wire Nordost set up.
Their new recommendation for bi-wire set ups is to only use two runs of speaker cable per channel...which of course from their perspective makes a LOT of sense $$$ wise!