"Sellers says that Zing Vision is akin to Sun Microsystems' DTrace probe, but is meant to be used in a production, not just a development and test environment, and is built into the product from the ground up so that using it imposes no extra performance penalty when people use it"
Ummmm... so are those words yours, or his? Either way, they display a lack of clue about what DTrace is. DTrace is not just a dev/test tool, it's designed for production environments. It's also designed so that it has minimal effect when in use. I'd love to know how Azul reckons their tool can be run with no performance penalty. Dtrace (and, iiuc, systemtap) have a performance penalty - even though it's very small.