RFC: plot.xts

Josh:
First, many thanks to everyone for this work. I've seen some
preliminary results, and they look wonderful.
Second, some questions before I dive in:
Does this subsume the xtsExtra package of plotting functions? Do we
still need xtsExtra, or is that toast?

plot.xts will be removed from xtsExtra in the near future.  Yes,
plot.xts and supporting function now in xts-proper supercede the
plot.xts in xtsExtra.

How would you recommend installing this? By devtools::install_github,
for example?

install_github is a fine approach

install_github('joshuaulrich/xts')

Finally, I depend critically on xts for daily work. Does this beta
release impact the non-graphics code? 

We use this code for production-critical tasks every day.  

The core of xts has the usual smattering of optimizations and bug fixes,
and has not changed substantially from a user perspective.  

plot.xts is substantially different from the old plot.xts, but the old
plot.xts didn't do much, which is why most users used chartSeries or
plot.zoo.

What's the appropriate level of caution here?

As always, YMMV, but this code has been under development and in use for
over a year, and I at least consider it stable and ready for prime time.

Regards,

Brian

Brian G. Peterson
http://braverock.com/brian/
Ph: 773-459-4973
IM: bgpbraverock