@Steve M: Yeah, if your goal is to replace multiple remotes, then a URC is the best solution. I'm a fan of Harmony remotes, personally. I haven't tried any of their RF stuff, as I've intentionally avoided any RF-controlled components in my chains. If you've got a stick gadget of some sort (FireTV stick, Chromecast, Roku stick, etc), pay special attention to whether the remote control you're considering will operate it, or plan to continue using the OEM remote for those incidental gadgets. And maybe continuing to use the Marantz app to control your secondary zones wouldn't be the worst thing to happen.
But for home theater operation, I'm not a big fan of apps for casual remote control. They're fine for very occasional use, for tweaking settings and so forth, but I prefer tactile buttons for typical operation. I don't want to have to look away from the show to launch an app to manipulate the volume, pause, navigate the cursor, whatever.