I took my iPad with iNavX to the San Juans in late Sept and to the BVI's in late Nov.
As a Canadian, my provider package gives me cell coverage anywhere in Canada, but I get roaming charges anywhere outside the country. So I turn it off outside Canada. In the middle of Bellingham Bay or Drake Channel, BVI's there is no Wi-Fi either.
The iPad worked great. Seemed fast too! ...And it does have course up!
I wouldn't mount it at the wheel - not too good in bright sunlight and not waterproof. But as a secondary system, real usefull. As skipper of a chartered C&C 115 in Bellingham, I used it to confirm for myself that we were where we should have been, without continually looking over the helmsman's shoulder.
...and I get e-mail and Internet too when we dock.
Just because you're paranoid ...doesn't mean they're not after you!