Tom Hoffman has an instructional video on youtube showing the specs for his "beast" whoopie.
Made with some xrings and some tenex prusik loops. Nice. Works really well, in a lot of configurations, as well as being foolishly easy to make. So, score one point for whoopies.
I also like r&r style basket slings when you can work them in, too. (overhead) They can be set and retrieved remotely, which is also a big bonus.