This is an oversimplification of the matter. In the end the technology doesn't matter as much as the actual implementation does. Both planar magnetics and moving coil headphones can be made good or bad. I have Sennheiser HD 800 which I use for binaural rendering and it is amazing for the job while being a moving coil (dynamic) headphone. I don't know what makes a headphone suitable for binaural rendering even though I'm working on a HRIR measurement software myself. I have tried HiFiMAN HE400S and Sennheiser HD 518 and there wasn't really any big difference between the two. Maybe a good sound stage and imaging are desired attributes but this is just a guess. HD 650 is known to have very small sound stage.