In my experience 2435HPL does not "push" gracefully, perhaps because of the inherent stiffness of Be. The literature suggests it operates pistonic up to 17 kHz, anyway, plenty high enough. Aquaplas would add significant mass to that diaphragm, which I wouldn't consider advantageous.

I'm now just letting them roll off above there on 2352 horns, and it's the best sounding two-way combination running here....