As for neodymium, it is powerful for its weight, which I think is its strongest point. The Deltalite series may offer reduced distortion over their ferrite counterparts, but I don't expect big improvements there.

Eminence tried to make drivers with shorting rings - the Magnums - but later abandoned them. That's an unrelated technology, but the point is I'm not sure Eminence is really focused on research and development. They are great at making good drivers with traditional ferrite structures but I don't expect them to do much development of other technologies. Perhaps in the case of neodymium, they were able to just basically mount a different magnet and that's it. But I'm concerned about thermal performance and things like that.

I prefer Eminence as a bang-for-the buck driver. They make very good sounding traditional ferrite drivers. I don't expect hi-tech motors from them, just good quality ferrite ones. But maybe their neodymium speakers are good too, and I should give them a closer look.

It might be worthwhile to get one of Eminence's neodymium drivers and their corresponding ferrite driver and see how the two compare. I have not done this, and probably should. It is worth taking the time to measure them and see. I'd focus on comparing electro-mechanical specs, the shift with temperature and the ability to withstand heat without damage. I'd be interested to compare harmonic and intermodulation distortion too.