We only use Gradle. We don't even load the M2E plugin.
Instead we have a custom plugin that runs Gradle (and fetches dependencies via Ivy).
m2e does not require the pom.xml, the pom.xml is what requires m2e for things to work - thus if no pom.xml, no m2e plugin used/loaded.
Thus you can go write your gradle files, but as things are now you will need to manually configure a lot of things since we can't see what features you enable/disable.
There is an Eclipse Gradle plugin that does some of the basics (setup dependencies, configure basic wtp etc.) but they are still limited in comparison to the m2e and m2e-wtp integration.