Well both have similar performance,from the brief comparision i did with the usual custom settings,they are quite even,if anything the particular samsung model* that i checked had a whisker better blacks,but the sony had a whisker better shadow details .Pausing the animated movie monsters dvd the EX400 shows fine detail in hair/fur a slightly better.
Didn't check the usb playback.
The EX400 is a steal @ 45k price in ebay.in & grey market.
*samsung lcd come with upto 3 different panels so the contrast,viewing angle,response time all vary depending on what type of panel one gets.