Best Practices

I guess if I need a new feature in a gem (present in a minor bump) and I don't want a major version change, I would just add a ~> version restriction and leave a reason in a commit message.

Another downside of not specifying version restrictions I've heard about in a podcast is a slower version resolution, especially with large Gemfiles like ours (re-solving cross-dependencies with different version specifications between different gems). However I can't find a reference to the source.

All in all I don't feel strongly about either, I'm willing to try a version-less approach and see if it causes any real problems. But perhaps I'd try it on a smaller project than pistachio.