Why should I care about RVM’s Gemset feature when I use Bundler?
You shouldn’t.
Well, if you want to, you can care about, of course, so I should better say “You don’t need to.”
I just listened to a podcast interview with one of the Bundler core team members who basically said that since he started using Bundler he stopped using Gemsets, because they are redundant.
Here’s a blog post that discusses the same issue, with some examples.