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If you are changing your URL structure when you change your CMS, you should 301 redirect your important pages from the old site to the new site. If your URL structure is staying the same, you do not need to worry about implementing 301s to maintain your authority/rank. Your authorship should not be affected as long as your are staying on the same domain. Changing code (in your case a new CMS) and design can have an affect on your rankings. Having a responsive design is great for users and that is what you should be concerned most about. 301s are perfectly fine and are encouraged if you are changing your URL structure. Your other option would be to maintain your current URL structure with the site redesign. Someone asked about a Website Redesign SEO Checklist a couple of months ago and Thomas Zickell provided some good resources. Hope this helps. Mike