how can a 1-page site have a proper privacy policy, complete contact details, about us info that conveys biz transparency, compelling / engaging / unique content and more...
you might be able to find special cases where this is possible, but in general, i'd put your chance of success at ppc'ing a one-page site at far less than 1 in 100.
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[edited by: buckworks at 5:39 pm (utc) on Dec. 30, 2009]
[edit reason] No URL drops please; see TOS [/edit]
The only way to answer your question fully is to test a one-pager, vs. more.
Always Be Testing
kaistudios- link to your site is not appropriate here.
Even with many pages, make sure your landing page is not one of those 30 screens high, testimonials / highlighted words / sales pitch video / $3000 of product for $29 pages that some internet marketers love to use. Google is hating them regardless of actual product or content.
Basically, it no longer matters what your site/product really is - if it resembles sites that typically get low QS, expect to get a low QS as well. That applies to look, and also keywords (like cash and debt and free)