We deploy beta and stable versions of our applications in a way where customers can be on the beta version of a subset of applications. Because of this, we essentially have two versions of each application deployed at the same time, and they all need to work with each version.
In order to run can-i-deploy using the --all option, each pacticipant pair has to be explicitly defined. Since virtually all of our applications are deployed in the way above, it would be a lot more convenient to have behavior similar to the --to option, but verifying against all versions of the --to tag rather than just the latest.