ok...you're partially right. but you are confusing isomerization/utilization with IBU's. Yes, both deal with hops, but IBU's are entirely dependent on the volume of the wort and although this has been debated, the gravity of the wort (hence why some people do a "hop tea". However, the point that you are missing is that although isomerization supposedly is "better" at a higher volume/lower gravity....there is a limit of saturation where you will be defeating the purpose of adding volume just for the sake of more IBU's. you will still have to boil down to the intended post boil volume, or at least very close to it to get to the IBU's that you actually want. Think about it logically. 1 oz of hopd in a 5 gallon batch and 1 oz in a 10 gallon batch. The 10 gallon batch will not have 50% less IBU's than the 5 gallon batch because the isomerization potentially was better, but the fact remains that the IBU's ARE LESS!!!! It's not linear....but they are less!!!!!