Oops, I never updated this, sorry. The feature was indeed nerfed, and isn't available anymore.
Before, you could use a pair of pre-2.0 armors and a pair of post-2.0 armorings, and if both had the same set bonus, you'd get both at the same time. For instance, the jugg 2pc PvP bonus was an 8% heal on intervene, and so by equipping two pairs of armorings together, you'd get a 16% heal on intervene.
Not sure if other classes still have this option?