People keep moaning about the gns going flat as it switches itself on in their bags.... I have never had that problem, if you keep it in mind and are careful how you store it you wont either.
Ive never had a problem with the gns and I've had it for at least 8 months so i recommend it
Ive only used it with air nav pro but it works flawlessly. I even use it on my tom tom app on the iPad, although that is a bit big!
I think from the light version i will definitely buy sd on iPad just wish i could have it on my iPhone 5 (backup) in case iPad freezes (although it never has)