I ended up getting a Nimbus Gray/Black Interior sport/entertainment model, and it's simply amazing. I was told that the ELS sound system in this vehicle was far more sophisticated and nuanced than the system in the RL... and remember, I thought the RL system was incredible. Well, this one is better than I ever imagined an automotive sound system could be. Remember when I complained that the Lexus Mark Levinson sound system was mushy and indistinct compared to the RL? Well, this is as much better than the RL's system as the RL was better than the Lexus. What's really amazing is what the unit does to MP3's... the Dolby sound processing really makes them seem like they're surround sound mixes, complete with crisp treble and rich bass. Plus, the MDX sport/entertainment will handle 5.1 DVDs as well as DVD-Audio, offering more listening options--and it also plays MP3s from a DVD-R, which means that if I don't want to use my iPod, I can burn 4.7 gigs of my favorites as MP3 files for more targeted listening.
The vehicle drives like a fine luxury car; it's powerful, smooth, and hedonistically comfortable. It also sits higher than a car, which is something I've missed ever since I got rid of the MDX a few years ago. This vehicle's suspension sounds like something from Stark Enterprises: it uses a ferrous fluid that responds to electromagnetic impulses by becoming thicker or thinner, offering more or less resistance to road impact, roll, etc.
Storage space/cargo space? No comparison; the RL was a little bit short on storage space, unfortunately (it was the only vehicle I've ever owned in which the glove compartment was too small to hold the owner's manual, which I had to slide under the passenger's seat to keep it out of the way).
The only thing that the RL had that is missing in the MDX is a proximity sensor for keyless entry and the starter. I actually have to hold the keyfob in my hand to unlock the key, and I have to insert the key in the ignition to start the car... very 20th century, but I'm more than willing to make that tradeoff in exchange for improved handling and a top-of-the-line sound system.