phenolic vs aluminum?
Do you mean symbiotik or pascalite?

These worn old ears used to detect a marginal difference between pascalite and aluminum with the aluminum being a tad more airy and extended in the upper regions. We're talking about a small difference here. Not really sure i would hear a difference worthy of remark today.

It would be interesting to see factory FR plots for both the 902 and the 909, but i only find one for the 909. Claimed FR for both is the same. But, that doesn't do anything to illustrate the subtle differences that "should" exist.