I used the Argus 5000 in my RV-4 a few times before I tore out the panel for its refit. The display is better than the gx55 gps I had. However, I never used it enough to learn the buttons very well. I ended up just using the gx55 even though its display was smaller and less conveniently located.
It's been awhile, but I'm pretty sure it has its own database. I don't recall ever updating it though.
That airplane was the first one that taught me the habit of using two moving maps simultaneously (originally the argus plus a handheld Garmin, later added a 430). I would keep one zoomed way in, and the other zoomed way out for "big picture." I still do that when I have a panel mount plus a handheld.
It really is an elegantly designed interface, just not real intuitive at first.