Der Jaeger
Generational EBUG
It shouldn't be impossible, but it might be more difficult than we think. The easy part would be keeping the rotational axis and center of gravity the same; but the modulus of elasticity is gonna get you. There should be a difference in the way a solid piece of rubber takes force compared to a puck with a non-elastic core section.
This is assuming they're taking any trouble to keep the weight and density the same. If those aren't the same, and according to Matthews and Spezza they aren't, the handling characteristics could be different enough that even a non-pro player could tell.
i assume your second point is true. I also think most of the energy characteristics of the puck can be reduced to an unnoticed level. Especially with stick advances