I don't know. But just for balance, another old Belgian, DeClerck, rejected the idea that all hop aroma from early additions was lost, arguing that wort retained the smell of hops no matter the boil length, hence late additions, he argued, were wasteful as they yielded little bitterness and added little to aroma. So he said.
It occurs to me that the aromatic particles carried up by steam are easily detected by us. We can't detect, with our noses, what is left in the wort, until it is later volatilized and carried by CO2 from the fermenter or our glass to our nose.
Perhaps it would require something like gas chromatography on samples at every stage of the brewing process to quantify how much of a given substance is lost or retained at each stage. (And we'd have to know just what substances make up each aroma, and I don't think we really do yet.) What does your experience tell you, qualitatively?
I have significantly reduced my boil off rate. I notice a tremendous improvement in the quality of malt flavor -- plenty of discussions out there as to why. I don't notice any real difference in aroma.