Navbox is an excellent VFR flight planning program and I use it for all VFR trips, all the way down to Greece but, due to the very bare map representation (avoidance of copyright payments for maps etc is what has enabled the low price of the program), it must always be used together with the real printed (or the real electronic) VFR chart which shows CAS, terrain (MSA) etc etc.
Navbox makes a very poor moving map product - precisely because the map data is so bare.
The two requirements are very different.
For
flight planning, you need something on which you can draw the route, and print off a plog (wind corrected, optionally).
On that plog you then write down the MSA and the planned altitude, for each leg.
These values come off the printed chart. They cannot really come out of anything electronic, like a Jepp GPS database, Navbox, Flitestar, etc. All these products have databases which are very hard to read.
For an
airborne GPS, you really need to be running the real VFR chart. For the UK, Memory Map running the UK CAA chart does this nicely, but requires a reasonable size screen. When you see the real VFR chart, you can use a moving map GPS for vertical navigation hints (alongside the previously prepared plog, of course
).
I have seen PocketFMS and it appears to be a good product but I don't recall how clearly readable are the vertical airspace annotations.