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The difference in interpretation by search engines will not be huge, but it's still worth sticking to the more readable hyphenated version. Also you don't risk the search engines misreading some urls due to new unwanted words forming from other words in a "no separation" scenario.
The PRO Web App is by far the most useful tool we have added to our SEO arsenal ever. It enables us to track and manage our efforts across multiple markets in such an easy and intuitive way.
If you already have a big structure running on a "no-separation" setup don't change it. The upside will not outweigh the potential disruption you cause. Do it for your new pages only.