I have used the Skymap II now for a year or so and find it great as a back up. The large screen makes it easy to read, there is the issue if you plug it into the cigar lighter and having the external antena you do have a lot of wires about, but if your careful in setting it up its okay.
I have found it very useful on occasions when I have been tracking close to the danger area's near Thruxton for ensuring that I don't accidently encroach them.
As a back up I can find no better, but I do agree that you can get lazy and start to look at them to see where you are. But a little will power and keeping a constant look out is much more fun than staring at the screen
Sometimes I fly without it but most times I like to know its there just in case.
I know you said cost isn't an issue but occasionaly Harry Mendelssohn have reconditioned units at very reasonable prices, so its worth asking. All completly refurbished at the manufacturer.