What's the status of vinum?

[Darren Pilgrim]

I'm currently doing a vinum RAID 1 on a box that runs RELENG_4_8.  For
what I do, at least, RELENG_5_2 "feels worthy" of a production box and
I'd really like to take advantage of some features 4.x doesn't have.
The threads on vinum/gvinum have me wondering if I should hold off a
bit.  What's the current condition of gvinum?  How well does
vinum/gvinum work in RELENG_5_2?  What are the features not yet
implemented in gvinum?  My eyeballs didn't capture any URLs for a status
page, but if someone can point me at one, that would be great.