So I just made a breakthrough with how the Vampire Lord handles equipment. Strangely, it would appear that your equipment IS removed when transforming. This can easily be checked via:

1. The unequip sound being made (it can be hard to hear.)

2. Wearing the Aetherial crown during transformation will result in a message popping up telling you that the stone was removed.

This means that, unless one uses the ring or necklace, it would be impossible to gain bonuses as a Vampire Lord as equipment is, in fact, being removed. However, I'm still trying to work out how the rings/necklaces work on the vampire lord.

You could check to see if the VLs health or magicka is changed by the rings by (un)equipping it in normal form and then changing. It shows health and everything with the perk tree. Repeat the opposite to see of there is a difference.

I've already done that. Unfortunately, my stats show up as green no matter what, and health/magic/stamina stay the same. As a result, it's difficult to tell if they're actually still equipped, and that the change of stats during transformation takes this into account, or if they unequip and there's simply some sort of check to see if the player was using the vampire artifacts during transformation.

You mean your stats are the same whether or not you transformed with one of the rings equipped? That would suggest that the rings don't give their health/magica effects when in lord form, only the special bonuses (claw damage and magicka regen, since the latter appears to be different from standard magicka regen enchants). I thought the rings did give their stat bonuses while in lord form, however. E.g. if you have necromage and transform with Ring of the Beast equipped, then your health will be 125 points higher than it is if you transform without that ring equipped.

Also, have you tried custom-enchanting the Amulet of Gargoyles and checking to see if the custom enchants carry over? Someone else has tested it with some heavily resto-loop-boosted enchants and found that they did not seem to carry over (although they did work while not transformed, and the extra gargoyle power worked while transformed). Perhaps try enchanting without using a potion to boost the magnitude?

The only effects that transfer over seem to be from the unique vampire amulets and rings. And yet enchanting the amulet of gargoyles doesn't seem to do much of anything. I'm starting to think that the game checks if those two items were removed, and of they were, then tack on the stat bonuses. IOW, the effects are not coming from the rings/amulets themselves, but rather a script that kicks in if they were equipped. Because further enchantments would not change this script, enchanting the Amulet of Gargoyles does squat for a vampire lord.

Just a guess, though.

That makes sense. The 100 health/magicka from the rings -- I assume, then, that does transfer over?