True... But it's been tested to hell in order to get certification whereas your average PC World/Dixons item is usually tested on the punter... Isn't that why my Garmin 296 was around - £4-500 more than the identical (marine) Garmin 276????
Your Garmin 296 is not certified if that is what you are saying. It is no more certified than your average PDA, or your home TV. As for why it costs more than a marine version you'll have to ask Garmin. They will probably tell you it's to do with the costs of it's database. Someone else will probably say it's to do with market forces.
Also.. when your PDA runs flat all useful data has to be fully reloaded... I'm not buying another PDA - they're c p IMHO!
I've used a PDA solution for the past 3 years or so. The main battery has run flat a number of times (when left around at home, not in the air), but I have never had to reload everything. Any decent PDA will have a good backup battery which will ensure data is stored for a long time. Mine has been on backup battery for a couple of weeks in the past with no problem.
A PDA by it's very nature does have weaknesses & strengths over a dedicated handheld GPS, but certification is not one of them.
Some of the advantages include colour screens, easily updateable to the latest version of software with all the new functions, provides a handy method of getting weather and notam data when away from base.
dp