I found that the DOF calculation cause a wrong look at transparent objects some times. It looks like they are unseen by the DOF calculation. A global option could help.
Attached an example - most wrong looking is the marked area. But also the label&cover DOF looks wrong, the little holes around the label should be sharp. Also attached a quick post-DOF test per Vray where I set the alpha of the cover to solid. This could be the expected result of the wished option.