The market share of Prestashop worldwide is 2.68% in May 2016 according to Buildwith.com. It represents 250000 websites worldwide.
Just 2 little weeks after Prestashop 220.127.116.11 was release, came Prestashop 18.104.22.168. Here is Prestashop 22.214.171.124 just after 1 week. Prestashop might look dynamic but let read between the lines. Today Prestashop 1.7 is not mature at all. As a business you would not like to put your activities at risk by implementing it in product.
You are probably very busy with all the sale period like Black Friday and Cyber Monday followed by the Christmas. I am pretty sure you don’t want to put more pressure on your business by planning a migration to this last version.
Due to a new theme and template framework written from scratch, current themes don’t work on Prestashop 1.7 at all. Not to mention that most of the modules that contribute to the frontend have to be updated as well. Many developers are complaining about the lack of documentation. It will take few more months to see a rich ecosystem of plugins that suit for Prestashop 1.6.
Recommendation: If you are running older versions, you don’t have to worry. The tool editor is planning to maintain Prestashop 1.6 until October 2018.