Downloadable products (Joomla/Virtuemart extensions)

[OpenGlobal]

Selling Virtuemart and other Joomla extensions as drectly downloadable products at http://www.openglobal.co.uk/shop.html, including an extension to facilitate "downloadable products".

Mostly using the default Virtuemart theme.

OpenGlobal

[tikos]

Could you please explain to me, which are the differences between this extension and  the core team's (iStraxx) VirtueMart Downloadable Products extension??
In other words, why should I prefer your exrension instead of the vm core team's extension (except that it is less expensive)??