Regarding the new generation CSEs, I would go for Retrevo.com (2.6 Million Unique Visitors/month – alliance w/ PriceGrabber) offering Social Media features & community evaluation for quality/pricing ratio. I would also mention PriceSpider.com providing Social Shopping services, price history graphs, personalized price alerts and a unique section of coupon/deal finders that you generally find on affiliate partners (supported by Digital River since 2009).

The problem for these new entrants is to reach a critical mass (i.e. minimum of 4 Million Unique Visitors/month) by making a partnership with an existing competitor, a leading portal or a Search Engine.

From a merchant perspective, it is already very costly & painful (even using ChannelAdvisor, Channel Intelligence, Singlefeed, etc.) to be integrated with the top 10 players. It is explaining why, they, including become.com, were regrouped in « others » category

To have more details about it, feel free to refer to the original presentation I quickly made on this subject available here: http://www.slideshare.net/MatthieuDejardins/comparison-shopping-engines-study-goals-recommendations-opportunities-to-boost-revenues-by-16-percents