Jim, I have eight new AGM's in my current coach now as I replaced the 6½ yr. old wet cells. Again, they are so clean and I don't have to add water.
The new coach that I'm looking into having built uses AGM's., the other converter uses Lithium Ion which are much, much, lighter in weight and last as long as 10 yrs. (and you need fewer of them).
The major difference between Lithium Ion (there are two types, these are not the airplane version), is that they don't go low like a regular wet cell or AGM battery..... you have perfect even power until they need recharging. When a regular battery gets low, it will make a motor that depends on the battery power work harder or put more stress on that part. Lithium Ion batteries have even power at all times until they need recharging.
Mark