mydataprovider

Hi all,
I recently got a web development project which involves shopping cart system and product listing. Now I am in the process of picking up right CMS, magento is out of options at this stage because it is too big and complicated to maintain and it requires a very good hosting environment to run a magento site. So, the best choice I may have is one of these two: prestashop and .net shopping cart platform, they are both powerful and relatively easy to maintain.
Is there anyone who familiar with these platforms? I would very much appreciated for any advise.

My prestashop store is version 1.4 at the moment. I want to use new store version 1.6. What should I do if I want migrate data from prestashop 1.4 to prestashop 1.6 one?
Please advise me a solution.
Thanks!