Not necessarily as the openwire protocol used between brokers is subject to versioning. The caveats are for resolved issues or improvements that require some additional features only found in a later release. With a version mismatch, these sort of features will not be available to you. You need to validate using a test to be sure. From a usability point of view, it is simpler to confine networks to a single version.
I address openwire versioning in a blog post just last week, hopefully that will explain the issues in detail, the remarks about client to broker communications are equally applicable to peer networks.