Here is my opinion, whether you want it or not.

I don't know much about EMS bags, other than I haven't heard anyone saying bad things about them. But, here is my philosophy. If you are seriously on a budget, but still want a light, down bag, then look at bags in the $100-$200 range, like the Kelty cosmic down series, or the Kelty lightyear series, or the Campmor bags. But, if you can spend $250-$400 on a bag, then you can also spend $400-$500 on a bag, and you might as well go for the top, like Westernmountaineering.