Hello Gnu!
I've adopted IceCat as my primary, if not only, browser and have no regrets. I'm using IceCat 38.3.0 on Slackware Linux 14.1 (Linux 3.10.17 KDE 4.10.5) on a Pentium Dual-Core T4400 @2.20 GHz w/8 GB RAM.
Today, while visiting a Yahoo Site, I right-clicked on an a trendy ad to open it in another page and it opened some kind of pop-up console, separate from the browser, showing that Outbrain was listing out my most recent downloads and the locations I downloaded them to. The latter is of great concern. I didn't pause to do a print-screen (I'm sorry). I disconnected wired Web connection, rebooted and checked for anomalous wireless connections before blocking the three ad-content providers. My data and privacy were of paramount concern.
I think perhaps the IceCat community hasn't considered how that this information can be obtained and that the information could be used in a pointed attack.
What I can do is use the hosts file to create a sinkhole for Outbrain, Taboola and Zergnet and IP Tables to block their IP's but that's really just a "band-aid" fix to a larger issue, one I wanted to alert the Gnu community to.
Have a wonderful Thanksgiving!
JOHN