@damn, correct unless the driver is selected via config is mostly harmless. If the driver implements a [#verify_dependenices](https://github.com/opscode/test-kitchen/blob/master/lib/kitchen/driver/base.rb#L104-L111) method there could be software checks that fail but this code is only triggered if the driver is loaded.

For the most part I'm not terribly dogmatic about driver choice that one would expect to see in a Gemfile. I'd suspect a reasonable default would continue to be the Vagrant driver. It might look strange to have a list of multiple drivers in the Gemfile, but nothing would be "wrong", perhaps just curious. How's that for noncommital? :smile: