Interspire shopping cart has been discontinued on July 1 of this year. Which is a pity. I always preferred it over magento (easier to use imho). And yes, we did use both for some fashion shops (shoes included). Now my preference goes to bigcommerce - interspire's hosted shopping cart baby brother.
I believe that magento commerce shopping cart will be much more reasonable to choose as there so many useful features for successful running of e-commerce web sites.