I'd certainly love one of these for a home lab. That's for sure!
I can see the whole ROBO deployment scenario. Even in single/several use situations, like you mentioned... such as for specific critical high-performing services that won't outgrow it. Anywhere else, I'd feel stuck with it... what happens if you start to outgrow the resources? How scalable is it? That's what would determine it's worth for usage in place of regular 2u deployment servers.
Maybe I'm just not a blade type person.
It's really meant for contained scenarios where you know how big you will grow. For a normal SMB, the issue is growing into it, rather than outgrowing it.