WooCommerce can handle that sized site no problem at all. And more. In fact, in the next version of WooCommerce 3.0.0 out April 3rd you will see many improvements speed wise as they have moved away from the slower wordpress tables for things and you’ll see marked improvements of 80-90% speed upgrades. Happy times.
Migration of data really wouldnt be hard either. Just ues the free CSV importer that is found in our knowledgebase under the compatible plugins article. It can handle product imports of any size and attribute the products to the right vendors accounts and everything. For importing everything else that isnt a product that’s easy too, ther’es other import tools for it and it’s all just simple database stuff anyway. Worse case scenario it might cost you a few hundred bucks to have someone migrate from Software X to WordPress/WooCommerce for you.
Hosting wise we offer hosting. You would have to have a dedicated server that sized website, most likely, and then that’d cost a couple hundred bucks a month to rent from there out.