Are they good pages? Significant in their niche, with unique content that can't be found somewhere else? Are they authoritative on their topic?
Only VERY RARELY does a visitor who lands on an article ever end up purchasing anything. So there is a bid difference in the INTENT of the user to the article pages than to the eCommerce pages.
I don't know if this your Panda problem. If they're good pages, it shouldn't be. If they're not particularly good pages - they're informative, but nothing that can't be found elsewhere - and you already know they're not converting into sales - personally, I would probably move them onto another domain or subdomain, if I couldn't come up with a way to make them convert.
You seem pretty attached to them, but if they're not converting to sales - why?
[edited by: netmeg at 11:07 pm (utc) on Jun 16, 2012]