Hi,
All the templates that aren't "optimized" for HikaShop 3, will work fine with HikaShop 3.
So the ones in
www.hikashop.com/download/templates-for-hikashop.html
could have more or less problems based on how you configure/customize HikaShop with them.
In most cases, the new checkout should work pretty well with any template since the views are different and thus the templates don't have overrides for them, however, that means that if you update from an old version of HikaShop, you'll loose the customization you had on the checkout in the template if you use the new checkout.
