netmeg - 1:30 am on Jul 18, 2013 (gmt 0)
Leave the NOINDEX on each page, and get rid of the block in robots.txt, so Google can see the NOINDEX.
(You do realize that this will also take you out of Bing and Yahoo)
NOINDEX is the surest way to stay out of Google. But you'll also stay out of the other search engines.
If you use robots.txt, you could still be indexed (only without a meta description). You're just telling Google not to crawl your pages, but they could still discover them other ways, for example via links to you.
NOINDEX deals with indexing. robots.txt deals with crawling. They're not quite the same thing.