This actually surprises me. I would have thought the PS3 would have slightly better sound (generally the extra storage space on Blu-Ray means that devs don't have to compress their audio as much) and slightly slower load times (since Blu-Ray access is generally slower than DVD access, and there is no HDD install for Dead Space).
It's possible that an audio difference was there, but it could be that the testers didn't have the right setup/environment to notice it. But the load times are a fairly cut and dry thing. I wonder if the EA guys have packed the Blu-Ray data in an unusual way to help load times, with the drawback being that it didn't leave as much extra space as usual for improved audio?