I've had the Marantz for a couple of months now. I didn't do a lot of research before choosing - my other components are Marantz so it matched (well kind of, for some reason they don't stock the silver model here in Indonesia) and I read the What Hi-Fi review.
Overall, I've been really happy with it and would recommend it to others - but I can't compare it to other similar devices as it is the only one that I have used.
I have some of my music stored on a NAS (Thecus N3200PRO) in FLAC format. The sound is great - I can't hear a difference between streaming these to the NA7004 and playing the original CDs. (My CD player is a cd6000ose, my amp is a pm6001 and my speakers are Monitor Audio Silver 8i, all around 8 years old.) But I can hear a difference in quality relative to CD when I play MP3 files (blind testing), even though they still sound fine.
The link to the NAS was also simple. Both are connected by cable to my router. The network set-up on the Marantz is easy. The NAS runs TwonkyMedia Server and the Marantz detected it automatically (and also detects computers on our network when they are running software with media server functionality). Very easy to play my music on shuffle. A little more painful to scroll through the displays if you want to find a particular album or song.
Aside from playing music from the NAS, I have installed the optional Airplay update. My wife streams music and podcasts from her ipad and iphone (simply a matter of selecting the marantz from the ipad or iphone) and you can do the same from itunes on your computer.
I have the sound from my DVD player and video media player run through the digital inputs on the Marantz (one coax, one optical) and the quality is excellent compared with what I was getting from the TV (and also better than running it from the audio out on the TV to the amp).
I love the internet radio function - a huge selection of stations that stream with no problems. KEXP Seattle is my favourite, but also many to choose from if I get homesick for Australia. There are also podcasts available in the same way available for streaming. Again, navigation is the problem when you have a small screen and so many choices, but once you set up your favourites it's easy.
And finally it works as a regular tuner, so it's replaced my old Marantz tuner.
All in all, I am very happy and would hate to have to be without it now. But, as I said at the start, I can't really help with the comparison with other options.