Earlier quoted context omitted.
As I said elsethread, I haven't yet considered production, but I just switched to chruby for my development environment rather than rbenv. I still use ruby-build when I need (I just needed a version not supported by ruby-install), but I have switched wholesale to chruby, and having found chgems in researching a different answer, I may look at using that as well. chruby really is the simplest possible thing you can do…
I'd argue that you don't need any of rvm/rbenv/chruby in production.
I'd agree. Something as simple as chruby makes having multiple interpreter/gemset versions easily usable from something like cron without introducing a lot more overhead, though, or having to remember to put all the variables &c. in place everywhere you need them.