TME, the Annihilator is superior in every aspect, except for the smooth implementation of RN6's sub bass. IMHO if the Annihilator 23 had any "weaknesss", it would be my perceived "lack" of one or two extra ounces of sub bass. In clarity, staging, resolution, mids / timbre and most of all the effortless, energetic and always smooth treble, Annihilator scores against RN6. With that said, I do enjoy the RN6 a lot and listen to them regularly. And everytime I do, they cause a massive grin on my face. Listening to almost every genre is effortless and works so well. As mentioned, especially because of it's controlled bass capabilities that can rumble deep and round if called for.
When I listen to the Annihilator, I'm stunned every single time. It always causes a "Wow". This is the Fir thread so I will leave it with that.
To me, they definitely are complementary and quite different in the way they sound. Even though the Annihilator 23 is the best IEM I have heard, I would not want to miss the RN6 due to it's ease in playing back all types of music effortless and engaging. It just feels "natural" and "musical" and allows me to focus on things (if I really want to) compared to the Anni where I don't have one single cycle of my awareness left to focus on anything else than my listening.