The other thing I dislike about SS is the shrinkage...it's slight, but enough that it can cause cracking on an armature. So again Aves wins as well as in the blending layers together...SS is a bit lacking in the layering department as well.
It's true that Aves cost is greater but if you consider that you can bulk out most sculptures with EPS, paper or aluminum foil first and just add a thin layer of Aves to skin it all of a sudden you'll find that the same amount of Aves goes way farther than SS.
Don't get me wrong, I still use SS, just not as much anymore....probably why I have about 10 bricks of it still in the boxes plus about a hundred of the colored mini packs still in their wrappers.
One issue many also find with SS is having to build an oven or cut their work into sections in order to cure larger pieces...that isn't an issue with Aves.
I have to say though that if you're not a "layers" type sculptor than Aves may not be for you...I also like DAS and LaDoll due to their self-hardening though they aren't nearly as strong as Aves.
then there is the smoothing issue...mineral oil or alcohol for SS but Aves, DAS and LaDoll all just smooth with water.