Yes, I actually have carried a hatch before. They are heavy, but if I can carry it, it's certainly not more than 150lbs. And like was posted, you have to compare that to the coupe's trunk, and rear glass. Not much of a difference anymore after you do that.
Anyway, my data was obtained from the
www.nada.com website.
It listed
1986 GT Hatch 5.0 3000 lbs
1987 LX Coupe 5.0 3000 lbs
1987 LX Hatch 5.0 3059 lbs
1987 GT Hatch 5.0 3080 lbs