Great info Dave - I've heard more than one person complain that the AGM batts aren't any better than standard batteries. That coming from folks who have installed them in their classic car.
Our 08 Escape battery lasted about 6 years. Replaced it with one from Advance Auto (their Silver line - mid range). I've had good luck with these - usually get 7-8 years out of them.
Dean - sounds like you have a current drain. Not sure about the remote thing - my remote is 20 yards away from my Dodge truck but it's a 2012 so may not have all the "communication" between the truck and remote that you have on the Charger.
Do you have a way to measure the switch off current drain? should be less than 100 milli-amps but 60-80 milli-amps should be great. You can even measure it with one of the cheap-o or free meters from Harbor Freight - just might have to disconnect the under the hood light while checking it. Disconnect the one of the battery terminals and put the meter in line in the current mode. Probably can google it and find a good description on how to connect it.
While you're measuring the current if you open a door and the interior light will come on and most likely blow the fuse in the cheap-o meters so be sure and only measure with everything off.
This is a clamp on version - was measuring current output on the Tbird generator so that's much higher reading 24.7 Amps.
Also possible that your battery has a shorted cell - it will charge and work under most conditions but any extended draws (even small ones) will make it loose capacity quickly.
Just some ideas - Eric
edit - looks like a decent article about finding "leaks"