Actually, Zencart can do cookie tracking for the cart, (
if enabled) and if the person comes back - it will repopulate the cart. If the potential client logs in, the cart will also be saved. If they have any saved carts, and come back and shop more - ZC will combine the carts when they sign back in.
ZC does take a fair amount of updating/changes to be truly 'friendly' - but it can also operate out of the box with no mods; however, you will still need to know a little bit about FTP, PHP updates, cpanel, etc. If you do go that route - you should check out the main Zencart community. They have boards to help you with troubles, should they arise, and also have additional add-ons for more functionality.
We are enjoying ZC right now, but looking at perhaps moving to the WordPress E-comm should they get a little better in the future.
Have fun,
- Joe
If you wanted to see some ZC examples -
www.fez-o-rama.com, and
www.disastersupplycatalog.com are two hosted here. Fez-o has many mods behind the scenes for image handling and externals, DSC has only shipping add-ons.