I really really really hate bugs. I have a pic of mine in my gallery. In the hot summer nights it's great having the options not to have to be inside of your quilt to keep the bugs off.
I like the idea of the seperate bugnet, because it allows me to use 1 hammock year around. I just add or take away parts as needed for the weather.
Pure weight wise I think attached is the way to go. But then again I carry a couple extra pounds to be comfortable.