I think it depends on how long you think you'll keep the piece, if it's just for a few years, then I'd do the concept RO, but if you want to keep it for a bit later in life, I think the Cabinet 4 will hold its appeal longer.
I would personally do the CP 4, the back fo the movement is quite nice, I especially like that its very traditional compared to the front and really makes it feel like two different watches.
I'm glad you have the great opportunity to make this type of choice,
Share more pix when you have it!
S