I have built several larger scale Ecom sites over the past few years. I use magento for most of my more serious clients. (Never even considered enterprise after I sat down with Roy rubin (CEO of magento) and Yoav Kutner and they explained exactly what it is)
I spent a month in India this year with an outsourced team and 2 months in Ukraine working on magento.
I will never trust volusion again, I have recently been in talks with bigcommerce though.