Furuno makes a great product. Most of my electronics are theres. I do not have any experience with the combo unit. I have use both as separate units and give them high marks.
I use on my boat the Furuno 582 and the Northstar 951, to me that is the best for what I do. I don't like the combo unit because if one breaks you lose both for repair. If room is very tight and you have not choice, then do what is best. I may go withn that combo setup on my bridge because I still have the lower station.