Here are some comparisons to give you a perspective.
This is for REAR Track Hubs with NO COGS mounted or lockrings.

IRO Hubs: 330grams - got this from Sheldon Browns site
LEVEL: 400grams (just weighed it)
Phil High Flange: Between 417grams and 432grams depending on spacing for the double fixed version - (Data also from Sheldon Brown's Site)

Since the Level cogs are beefy, they add an additional 75grams when mounted. But even thoug the Level Cogs are heavier, when you add a "normal cog AND lockring" you're looking at a similar increase.

So Erich, perhaps you should lift a Phil hub next time you're in the shop, but use your other hand so you can get an even workout..