Oh Tony try your Delorme SE at about 10 mile Haines highway where there is no gps coverage
Mine has been well tested as far south as Ushuaia and the rest of South America and up as far as Toktoyoktuk on the Arctic Ocean in Canada, over a fair bit of Alaska and south to southern Mexico, and a lot of Europe including all parts of Iceland and the Delorme always gets through. Cell phones - waaaaayyyy less coverage including no coverage over large areas of mainland USA
The Delorme isn't perfect but its tracking feature means anyone on the list gets updates on your position every 10 minutes, and two way text messaging is possible with any mobile number or email address.
Still, if you always restrict your wanderings to Main Street USA then a cell phone should be OK.