I've got a heap of 6pin redel/lemo sockets from an old preamp project, they would be perfect for i2s (i.e. 3 twisted pairs), send me a pm if interested.
agree with the op, these would have to be better than rca for i2s, plus you could carry all 3 signals in the one cable...
There used to be an australian agent for lemo, not sure if they are still around of competitive with farnell: lemo@johnbarry.com.au