Gustav Kiburg has done an extensive test between these two lenses, posted in a Dyxum.com forum thread:
http://www.dyxum.com/dforum/comparision-test-sony-70-400-vsminolta-400mm-f4_topic46212.html
It’s well worth checking out.
– DK
Tag: 70-400mm
Sony 70-400mm vs Minolta 400mm f/4.5