Ah ha! So we're looking at this thread again?
http://uk.gamespot.com/pages/profile/show_blog_entry.php?topic_id=23916169&user=skektek
Yep, the DVD drive in the x360 is faster. Personally the installs don't bother me. I realise not everyone has put a bigger HD in their ps3 though and it's annoying that some installs aren't optional.