How Many Devices Do You Use?

I am a minimalist and like to keep things simple - I have a Macbook Air 2013, Nexus 4, and a PS3 - each serving a purpose. I would throw the Fitbit in there but its a niche device, however its among the devices I use and carry with me everyday (PS3 does not see as much use or travel as the rest but it is an important element in the arsenal).

My Nexus 7 2012 WiFi has been collecting dust since I got my MBA - I use to use it as a phone backup and for the screen size to display brochures to clients and as a car GPS - nowadays my MBA and N4 take on those roles respectively.

I remember when I using the Nexus 7, I often saw repetitive notifications on both devices, and since Calls, SMS, Whatsapp, Camera, and Google News are only exclusive to my phone, it meant I can't pick the N7 over the N4 and had to maintain them both simultaneously ie keeping both charged and with me at all times. When I am at home, I would rather go to the MBA for the full web, chrome extensions, keyboard, desktop multitasking and apps.

What I am trying to say is 3 devices (Ultraportable, Phone, Gaming Console); 4 with Fitbit included, each serving a different purpose with little overlap to reduce redundancy is the magic number for me. So I question the existence of the Nexus 7 or any other Android tablet for that matter in my "ecosystem". Unless something can completely replace one of those 4 devices - I don't think I will be all out for it.