Have you tried the Marmoset milk scene tutorial? The idea is to render a super high res image using both additive and dithered transparency, then scale down the image in Photoshop. I tried it and it works really well. Tutorial: http://www.marmoset.co/toolbag/learn/glass
Still amazed by how clean it look while there is a normal only on the wheels ... How did you baked your occlusion/cavity without a high poly ? Straight from the low or did you made it by hand ? And how was the PBR "conversion" ? I saw this tutorial about it : http://www.marmoset.co/toolbag/learn/pbr-conversion , but…