i recommend interspire shopping cart: http://www.interspire.com/shoppingcart nothing but great things to say about their product and service!
Hey, Have you tried Magento? It's a booming shopping cart technology. As a SEO savvy guy I prefer Magento cart the most because It's the best SEO friendly shopping cart among all. It's SEO friendly coding helps your custom Magento website to gain high rankings in SEs. It also gives you Auto generated Google Sitemap, Meta for your products and category pages and much more…
The post here is rather old - any chance of sharing your final decision with us? Many platform can suit into the above-mentioned requirements, that is why we're curious