Transmapped brows and lashes allow for better variation.  Plus modelled brows and lashes are just added more vertices that have to be smoothed and rendered.

I wouldn't be surprised if they rendered her in Carrrara because maybe they are making her so that she has multiple functionality in different programs.  It would certainly be advantagous for DAZ to do so since they are acquiring so much software.

I just think the timing on releasing her is getting down to the wire...especially in the holliday season.  Release her when people are hungry to buy, but not when they are burnt out on shopping.