Anyone use Shopping Comparison sites to Gain Authority?

With an eCommerce store is it a good idea to have all of your products all the shopping comparison sites.
Would the links back to each of your products be good link juice and help you build authority.

Also would you put a link in your footer saying something like "As seen on shoppingcomparisonsite..." etc with a link to your business on the actual shopping comparison sites.

If so would you make them nofollow.

Anyone shed some light on this?