Thanks for the zero balance thread.
I would still consider to store my bitcoins on my smartphone since I always keep the backup of the private key in a password protected file and store it both on my smartphone and my PC. So I guess it is safe to store the bitcoins in a smartphone wallet.
You plan to keep the backup of your privatekeys on the same smartphone you keep your wallet?
Back-ups are supposed to be in a different place, if something goes wrong with your phone you lose your wallet and one of your back-ups, what's the point of it?
I would go for a nano s with the recovery seed stored somewhere safe and not in digital form.