I have just done/doing some playing with frozen (commercial blend) compared to room temp storge for some fun Room temp is getting flat at 5 weeks frozen is better just when first opened but gets old really quick if you leave it a few days after thawing. I also have a fresh bag I got this week and the difference is fairly noticeable. The old ones are not bad just worse than they could be :-/
I have had some lightly roasted ones lose their zip at 2 weeks but I am not sure if that is the bean or the roast.
Only conclusion is that fresh is best :)