That wouldn't be stealing though would it? If anything it would be the DH copying the DE. DH stole Metamorphosis from Warlocks only because Warlocks no longer have it lol. If Demo still had their version of Meta, then the ability wouldn't have been stolen but also copied.
And I would hardly say that my idea, Infernal Jet, is a mere copy of Soar. Sure, the concepts are the same, but aren't numerous other abilities across the classes? If it were only aesthetic changes I would understand, but this is not just a reskin because there are mechanical differences.