We were really impressed by Enermax Liberty ECO 500 W, and it is always good to see a manufacturer improving their product line. Liberty ECO series has absolutely nothing to do with the previous Liberty DXX series: it uses a completely different internal design that provides a far higher efficiency.
Everything is perfect on Liberty ECO 500 W: high efficiency (between 83% and 85% if you pull up to 300 W; pulling 400 W you will see 82.5% efficiency; and at full load efficiency drops to 80.5%, but definetely this product wasn’t developed to work full time delivering 500 W), very low noise and ripple levels, right number of cables for the mainstream user and excellent price (USD 100 at Newegg.com).
The only reason we would recommend someone to buy a different product is if you need even more cables or if you want a product with an even higher efficiency. In this case, however, there is no other option but looking for a more expensive product.