The title kind of says it all. I'm asking, because this Performing certain operations without clearing register question seems to be sufficiently answered https://stackoverflow.com/questions/54255/in-vim-is-there-a-way-to-delete-without-putting-text-in-the-register here.
None of the above.
Closing is only for questions that are unanswerable or that are off-topic. The fact that a question has been answered elsewhere is irrelevant.
Lack of research is a valid reason to downvote, but just because the question has been asked somewhere else on the Internet doesn't imply a lack of research. (For one thing, has this elsewhere question been answered satisfactorily?)
Copying the answer is a possibility¹, if there's an answer that's really great, but it shouldn't happen too often. The whole point for this site to exist is to be a better place for vi questions than SO. If SO is the place to go for vi answers, there's no point in having a site dedicated to vi.
Many vi answers on SO are somewhat minimalistic. Don't just copy an answer that says “press kkjjhlhl21i”: explain why it works, link to the manual, suggest additional plugins that help with the task, discuss portability across vi implementations, etc.
Especially in the early beta, don't be content with adequate answers. Aim for awesome.
¹ You may always copy Stack Exchange answers, with attribution.
I think the correct response might be to link the off-site response in a comment (although I could be convinced that linking it in an answer is better).
I don't think that copying an answer is a good idea. It feels plagiarism-y (despite the fact that it's all under CC). Plus, which answer should a google search turn up?
Writing a better answer is...well, better, but sometimes that's just not feasible.
