Jim:
I use IFLY for Android on my galaxy note 3 and with the 5.5" screen it works just fine. I have direct sunlight that comes in from the top of my cockpit and I can see it just fine.
The developer has increased the size of the instrument boxes so what used to be hard to read is now easy.
Verizon offered me a 7" tablet for "free" but for 10 bucks extra a month. It worked OK but had other issues so I rejected it.
My Note 3 goes on my knee board and has served well for almost a year.
I don't see the need for a tablet since what I have is working OK.