JohnE,
Good information. I didn't know the Espar would do that to Exides. We had a very mild winter here in CT, so I can't say the batteries were really put through their paces. I'm not sure, but I think the current draw is pretty low, 5-15amps if I recall. But even a dome light over a long enough time will really drain down a battery. I've also seen posted here on the TDR that you should make sure the heater fan in the cabin is set on low. It will suck down the juice too.
My father had a heater on a 36' sailboat, not sure which one, but he swore up and down the Espar was a better heater than the Webasto. Either he wished he'd spent the money and had one, or he was very glad he did... (?)
I got the remote for it a little later, and I have to say, it isn't what they show in the owner's manual. If I had to guess, I'd say the manual reflects what they sell in Europe, the FCC probably has other ideas about frequency and strength a remote should have, so you end up with a generic American model.
I got my exhaust brake this summer so I haven't been able to use it for warm up yet. I agree that it helps get things up to temp sooner, but so does putting the Cummins to work. That's still the fasted way to warm the engine. The exhaust brake puts a light load on the engine at idle, making it call for more fuel, so there's more heat getting made.
The thing to avoid if you want your engine to last 'forever' is wash-down of the cylinder walls as fuel condenses onto that cold surface. My guess is that, while the exhaust brake will minimize that time, the pre-heating will eliminate it.
Matt