While some will not see a value for AGM batteries, the following advantages are why I have 440Ahr of AGM batteries in my TC, which is used both summer and winter for boondocking.
Charge acceptance rate for AGM batteries are significantly higher than flooded lead acid batteries, resulting in less generator time / fuel needed to recharge to ~90% SOC when it isn't sunny.
Under normal charging conditions AGM batteries don't vent allowing them to be inside (if you are comfortable with this). A 60-70F battery has significantly more Ahr capacity than a cold battery, in a vented, unheated battery compartment. Don't have to replace a non-temperature compensated converter / charger with a temperature compensated one and temperature sensors, if you store the batteries in the heated camper.
Non-venting AGM batteries don't spill sulfuric acid from the battery into the compartment, independent of orientation.
Non-venting AGM batteries can be placed out of the way, without the concern for access for the routine maintenance of adding water to flooded lead acid batteries.
Self discharge rate of AGM batteries are less than flooded lead acid batteries. Significant if you don't use your battery during the winter. Discharged battery electrolyte freezes and destroys the flooded lead acid battery. AGM batteries maintain their charge, and even if frozen, not sustain damage.
