I have owned both an Antec Sonata and a Lian-Li V1000.. I seem to have better luck at cooling the Sonata because I had a 120mm-fan PSU that helped with the venting, so essentially I had two 120mm fans in the back of the Sonata blowing out and one 120mm fan in the front blowing in. In the V1000 the PSU does not help with venting the main case interior because the PSU is isolated in its own compartment. My case temps with the Sonata when I had my P4 3.0C system in there was 30C when room temp is 25C. In the V1000 the case temp was 32C.
Small difference, but every little bit helps I guess.