Dome mids really have a special place in car audio. Being self-enclosed, you don't have to worry about trying to stuff a driver into too small of an enclosure, and the resulting heavy low end resonances which can muddy up the midrange. It's also nice to have a solid 90dbwm+ sensitivity, rather than the traditional low 80's you'd see from your typical 3-4" mid.
My favorite dome mid coming into this review was the Usher silk dome. It had an excellent mix of detail and body and was well built. I have to say that I have a new favorite now, and it's the Dayton rs52.
The rs52 is well built, with a large aluminum rear chamber and flange, and a copper shorting ring above the pole. Clarity and realism is unbelievable, and among the best I've heard to date in a dome mid (or cone above ~600hz). I also felt that coloration was extremely low, and not nearly as cold sounding as some titanium and aluminum domes I've tested before. Notching the breakup above 10khz yielded a slightly more neutral presentation that I doubt many would notice in their cars. Some may even prefer the brighter, more detailed sound from not filtering it.
If I had to pick something I didn't like, it would be the low end dynamics... although it's certainly arguable that domes weren't designed to play optimally below ~500-600hz. There is a slight amount of resonance in the rear chamber and the driver audibly breaks up when pushed hard. For car use, I'd recommend no lower than a 4th order highpass at 300-400hz. For those that push their drivers hard or have an extremely discriminating ear, 600hz would be more ideal.