I've done some research and found some info for different fillers, with comparative pricing.
The PL S40 I used is only Shore A 28-32, and $7.99 a tube.
3M Auto Glass Urethane Windshield Adhesive-Medium Viscosity,
PN 08693, Is Shore A 50-55 and about $15.00 a tube.
3M Windo-Weld Super Fast Urethane, PN 08609, is Shore A 55-60 and $26.00 a tube.
I think 3M 08693 is the winner, and will go in my old mounts soon.