Hi Rick,
Welcome to the Breitling forum... You & your son are surely looking at 2 fine watches. :thumbup1:
Regarding the water resistancy. Each brand really defines the limits of a 100m watch differently. For Breitling, they say the 100m watches are good fir swimming, shallow diving, snorkeling & free diving (not full scuba). When you say "wend down more than a few feet" what depth are you talking about? If it's 30 feet or so, I wouldn't worry about it. If you're scuba diving deeper, then it may be a problem.
On your second point, I've read stories where they've been used to find people, but never firsthand knowledge. As Tricky said, I don't believe any of the members have them here. If so, shame on them because they surely haven't posted any pictures for us to see... :wink: :biggrin:
As Tricky said, if you do use it, the antenna & transmitter battery will been to be reset / replaced by Breitling. I don't know what this costs, but can't imagine it being excessive. Once the transmitter is activated, it'll continue to broadcast until the battery is dead (48 hours). FYI - on a side note, if you plan to buy pre-owned you can tell an Emergency's transmitter has been used because you'll see a red ring around the antenna screw lock. It automatically 'pops out' when activated. So if you see one with a small red ring at the bottom of the antenna crown, it'll need the above servicing.
On the 3rd point, it's just personal preference. The Emergency (digi-ani) has a range of 100 miles assuming the search aircraft is at 20,000 ft. The Emergency Missions (chrono) range is 90 miles at the same 20,000 ft. Other than that, they're pretty much the same in different packages.
One note. You said you go 'off the beaten path'. Are you talking about hiking & such or are you planing to use this in a plane? Are you looking to use this for emergency while on the ground, such as hiking, mountain climbing, etc? reason I ask is the frequency it uses is reserved for aircraft emergencies. I believe it is restricted to aircraft use only. If you won't be flying, I'd recommend checking with the FAA to see if it can be used for any emergency, or just aircraft. Remember, it'll transmit about 100 miles to a plane that's looking for you at 20,000 ft. So someone has to already be looking for you for it to work. Also, and again just FYI I believe the aircraft frequency is being changed in the next few years. I really don't think this will be an issue as I'd expect Breitling would adjust the transmitter to the proper spec (it's not that big a deal to change the transmitter freq), and I'd assume they'd do this for no or nominal charge. BUT, you may want to ask a Breitling dealer to ask Breitling what their plans are for that should you decide to get one.
Good luck! Do let us know if you get them, and if so I believe you'll be WTF's first! :thumbup1: So do post some pictures for us to enjoy!