Anyone who is interested in this can read that Sterling experiment
. If they do, they will find that your interpretation of what you read is in stark contrast to what he published.
For example, he was not charging a 100Ahr battery with 160A of current like you keep claiming. His graphical data and writeup clearly show that the most current ever accepted by that battery was 160A - and that only at the beginning. His data shows that current dropping quickly to 60A, and would have been below 25A rather quickly if he had let it go - you can infer the speed of that by the linearity portions of the SOC graphs.
He was only able to even do this because he chose a small battery and had a very large charging source that could keep up with the battery's natural acceptance rate and drive the battery to 14.8V quickly. His point in doing so was to show with actual data that no harm is done by using higher absorption voltages during charging.
He then makes the very clear point that it would be rare indeed that anyone would actually have this level of charging ability in practice. However, he demonstrates that even with lesser current charging sources, using higher voltages allows more usable current to be restored to the batteries before full charge is reached. By higher voltages, he means the voltages in common use today - they were not necessarily in common use when this was written.
In other words, he is simply showing experimental results supporting the charging regimes in common use today. Since Lloyd posted Rick's thoughts on amp-hour law, it is obvious that Sterling's results also support that. You can see the Epsilon curve clearly in Sterling's first graph.
Now, here is where Sterling gets tricky in the name of marketing
, and where your comprehension may have been confused. He does not provide any time scale when making his point about charge acceptance speed on his first graph, and chooses to make his second point about charged stored on his second graph by picking a point in time that did not represent a full charge of the batteries - and then running those different SOC's flat. If, instead, he chose to fully charge the batteries at different voltages (13.8-14.8V), he would have found that all of them would run the load for the same time.
Sterling's results are as true for AGM's as they are for FLA's - it doesn't matter the form of LA the battery takes. It also doesn't matter that he was not using a deep cycle battery. If he had, no harm would have been done to it - it certainly would not have boiled hot like you suggest - it merely would have not shown his point so dramatically. Instead, the surface charge on it would have built so quickly, that the current acceptance would have plummeted. Also, the differences in charge stored would have been less in the short time he chose for his second point.
So, in summary, Sterling proved commonly accepted physical charging characteristics of a FLA, then did a bit of slight-of-hand to imply that his chargers could perform this function while "others" may not. None of that is false, it just isn't the sole truth.
Where Sterling did good was in helping to convince people that large charging sources and higher voltages are good things - particularly when the batteries are not being fully charged each charge cycle. I see too many boaters with 600+ Ahr battery banks and 20A chargers set at 14.2-14.4V, and using 50-75% cycles. He seems to have failed to make that point with you, but it is no reason to call him an idiot no matter which dictionary you use.
The debate about whether FLA's should be charged at 0.1C or 0.25C is meaningless because it is a rare boat that gets to 0.25C, let alone above that. Additionally, as others have pointed out (so you don't have to take only my word), the battery will determine the acceptance rate if the voltage is limited. There is no such practical thing on a boat as too "large" of a charger. Mr. Sterling is making the point that there is such a thing as too small of one.