I only test drove a 540, but my impressions match your experience. My only real complaints about the V70T5 are the low-rpm performance and the uncomfortable steering wheel. It is significantly better than the 540 in many respects- notably the seats and the intuitive dashboard controls. I think the handling on rough roads is superior, too, and at least the equal of the 540 on smooth roads.

Thanks for taking the time to post your observations- it was an interesting read.