I voted radius rods because they are easily replaced with a spherical and can be adjusted for castor in a much wider range without binding than the EG/DC arms with 2 bushings. I am also biased because I've owned 3 DA's

In terms of performance they will be very similar. I can't back this up but I believe the EG/DC suspension is mounted higher on the chassis than the DA so you can get the centre of gravity (CG) lower without running out of suspension travel. When your tyre is lowered to the guard (tiny gap) you have maybe 2cm of space between the upper control arm and the fender wall. Not good...

With no radius rod you probably don't need a very big front cross-member. I've never seen a EG/DC front cross-member but I imagine it is smaller than the DA's. Moving weight closer to the CG is always a good thing.

A likely possibility is that the EG/DC lower A-arm is cheaper to produce and they simply want to save money. They've (and any other business you can name) done it before; DC5 Macpherson Struts a perfect example. Another is the new Civics with their terrible rear suspension. Money money money.