I did find out that a c/f hood for an E46 M3, which is noticeably larger than our 'teg hoods and has more curves and bumps, weighs in at around 22lbs, so I can't imagine it would be any more than 12 or 15lbs for the 'teg. There's a post, here, where a guy claims his c/f hood weighs 9lbs...granted judging by his name he has an EK, but the hoods on those are barely smaller than 'teg hoods.

now, VIS racing claims that their c/f hoods are 20-30lbs lighter than stock...so that means that stock 'teg hoods are anywhere from 30-40+lbs

bottom line is that yes, getting a c/f hood WILL make a slight reduction in the weight of your car, and if you like the looks of it, then awesome, two for one...