I had whoopies on most of my hammocks, but am in the process of converting them to dogbones and straps with elephant trunks. I got 12' straps from Harbor Freight and Attached Elephant Trunks and attach them to the dogbones that are attached to my hammock. I have also added Dutch clips to make it much faster to hook it all up. I love this system much better than using whoopies.
Whoopies don't work well with trees close together.