Originally Posted by Mustardman
To expand on Ferret's explanation - a biner is designed to take forces pulling straight along the long direction, but there are lots of ways this setup could pull in other directions. The most worrisome in my eyes is the chance for things to shift around while the hammock is not loaded. A little wind whipping the suspension lines around, and they could easily end up pulling on a weird direction and doing something like pulling sideways on the thinner section of the metal.
This is one of the most common types of failure for rock climbers - if you do a google image search for "cross load carabiner", you get some nice images on the first page of biners that broke because they were'nt loaded correctly.
Again, I'm not saying it won't work - I am warning you to be careful about it.
If there are any other knuckleheads out there that are still confused about this...Mustardman's suggestion of the Google "cross load carabiner" search will make it crystal clear. I already knew this but apparently didn't know the correct terminology for it.
Thanks Mustardman. Miguel