So today I decided to really put the test to my 1/8 whoopie slings. They held great, the aluminum toggle that I cut from an old Everest arrow, lets just say it didn't make it. So Biggin, if you are over 300 lbs use a solid toggle and save yourself a rump shaking.
FYI I'm 360 lbs and really test my equipment to the fullest. I try to break it just so I know how reliable it is. If its tuff, ill get another. if it sucks, I try something different. Today I jumped straight up and when I landed I centered all my weight on the hammock. Before I jumped I tried to come up with a hypotheses and I was thinking the fabric was going to give first, but I was wrong. The toggle buckled and snapped out of the webbing and took off flying. Still haven't found it. Ha. I think I could have killed a horse if it was struck by it. If your new to hammocking here's what I recommend.

1/8 whoopie slings with 18 inch lock

Tubular webbing 3/4 inch with a solid toggle

1.9 nylon or canvas with no channel, gather the ends and use a whipping knot then larks head your whoopie below the whipping knot. Trust me this is way stronger than a channeled end. If you do this, you could pretty much jump off a building land in your hammock and the tree trunks would snap before your hammock does. Don't try it. I want to first.