I'm at home with vim (10+ years + a finely tuned and pimped up ~/.vim/) and have used vimoutliner a lot, but it goes in the opposite way for me: org-mode is one of the reasons I'm considering giving emacs another chance :)
I disagree, Viper mode is a very thin imitation of a few Vim commands. Slightly too thin for my liking, even on the most compatible of modes :p
Besides, to really experience the benefits of Emacs you have to dive right in. There are many Emacs features I wish Vim had but I fear many of these diminish in value when taken out of their natural environment. The reverse can also be argued to a lesser extent.
With the introduction of additional data structures (lists, dictionaries that can also be used for prototype-based programming) in vim7, I don't think vimscript is that bad. And you can also use python/ruby/perl/tcl/scheme/lua/whatever when you have the proper version of vim.
Whilst being able to script vim with lots of different languages is great, it's a shame it's not just one, since nobody really wants some hybrid beast linked against 6 different interpreters just to run a few scripts in one's editor.
Is the intent to use the same format as, or otherwise interoperate with, org-mode for emacs?
Also, worth comparing with vimoutliner? (http://vimoutliner.org)