First, for the original questioners use, any battery should be fine. The alternator will provide all the power you need. Your battery will simply get the vehicle started and not be needed to provide continued amperage. Towing virtually anything does not increase current draw to the extent that the tow vehicle battery capacity comes into play. Unless you are running refrigeration (not the kind in an RV, that still uses very little).
Second, yes we are serious. Did you know the Diehard Platinum is an AGM? Thats right Absorbed Glass Mat. Virtually all claims made by Optima are common to all AGM batteries. They all have low internal resistance, accept a charge fast, maintain stable voltages at high current draw, high energy density, and have a low self discharge rate. They are all also very expensive. The primary difference is the Optimas spiral wound design. This may offer some benefit to vibration resistance. However, there are many other ways to accomplish this that may be superior (plate edge insulation, intercell connection size, thickness of the plate and the like) without the inherent sacrifices.
If you do run high current draw, low duration applications such as amps any AGM will preform exceptionally. If the current draw will last much longer such as extended winching, we need to consider battery capacity. This is not CCA but could be expressed as Ah capacity or Reserve capacity (not the same, they are messured using different test procedures). This is primarily determined by plate surface area. This is also where Optimas are lacking. Remember the spiral design, their "deep cycle" batteries sacrifice total capacity for life span while there starting batteries sacrifice life span for current.
Im not saying Optima isn't a fine battery and will work wonderfully for most situations, it just isn't the hands down winner by any means. The Die hard Platinum accels at Reserve capacty for a starting type AGM. This would only be needed if you play that stereo for a long time without the engine running, winch for extended periods or have to crank for a very long time to start the engine. Life Line may be the finest brand made anywhere at any price for deep discharge AGMs. First decide if you really need an AGM. Like I said, they are expensive. Especially Life Line.
Finally, what exactly does "non checkable" mean. I assume you mean maintenance free which doesn't really exist. It truely means maintenance prohibitive. All batteries gas some even gels and AGMs. Its a fact of the chemistry involved. With the so called maintenance free you simply can not replace the lost water. Optima claims that their battery does not gas if charged under 15 volts under most conditions. They do not define most conditions. Gassing is very temperature dependent. The defacto temp the industry uses is 80 degrees. Most AGM manufactures say they dont "significantly" gas at 80 degrees unless charged above 14.4 volts. Underhood temps in most vehicles significantly exceede this temperature. Fortunatly most alternators regulate between 13.5 and 14.5 volts.
So what I use isn't really a question. Diehard Platinum in the Explorer- I winch for extended periods and their warranty is pretty good. Life Lines on the trailer- large battery bank with complete solar charging system. We do alot of dry camping but still want all the conveniences. When I finally do draw the Life Lines down about 50% we are usually headed for a new location and charge off the Explorer alternator via a 0-2 (that is correct, not a 2-0) cable all the way back to the trailer.
Sorry to ramble, but like I said the Optima isn't the Cats Ass. Its just a decent battery for those that feel the need for an AGM. There are alternatives, and yes we are serious.
