Define "sufficient" ... ;-). I started with a GPSMAP196 and was quite happy with it for a long time, until the first iPad came. The current Retina ones are stunning and carry a lot of information, for my feelings sometime far too much for piloting.
I did fine with the 196, but these older devices present a very limited set of information and need less viewing attention, compared to smartdevice moving maps. With the 5S you will find yourself frequently zooming in, zooming out, panning etc to fulfill your needs - having georef VAC on a 5S with some ICAO charts underlying can be too much useless information.
You could do with a 5S mounted, it may suit you for cruise, but keep the iPad on the kneeboard for situations more complex, or when you need bigger overview.
Last edited by ChickenHouse; 18th March 2015 at 14:57.