I've just recently changed the URL structure of many of my store's product pages. These product pages have several hundred Facebook 'Likes' and 'Tweets' but if I want to keep the number of Likes and Tweets I'll have to keep the widgets' URL as the old one and create a redirect for the old URL to the new URL (so that friend of friends who follow the link will be brought to a working product page).
What is the method of best practice here?
Is there any harm in keeping the old URL's for the widgets but on the new URL page? Or should I just set the new URL for the widgets so that the URL is the actual and new URL of that particular page - and lose my number of Likes/Tweets?