I have an Airbox Foresight installed on the instrument cluster and wish I had never bought it. Every time I synch it to the laptop, it crashes when I try to use it, yesterday it could not get a GPS signal whilst my 10 year old Garmin handheld worked faultlessly, you can't read it in bright sunlight and the touch screen is fiddly to use.
My IPAD2 with its built in GPS running AirNav Pro works every time, is easy to use, has never yet lost GPS lock and because it is on my knee strap can be clearly seen as the display is huge compared to anything else. I can also easily switch to uncluttered topo maps in flight if I want to. The ANP suppliers seem to provide excellent support and publish free upgrades almost weekly. Also passengers love to hold it and tell me which way to go!
I know which one I prefer.