I have been in contact with slingrings about the strength of their small aluminum rings. Just thought I'd share the info:
In the independent testing that we have had done, the small rings break at 2000 pounds. If you are planning on selling the hammocks, I would recommend having your own testing done as well, though I am putting together a packet of testing information that I will have ready in a little while if you would like a copy of it.
I hope that helps to answer your questions.