If it helps, I have a 920 ah bank (Deka FLA) charged by two Balmar 100-amp alternators. It takes 4.5 hours to charge them to 100% when discharged to 50%. Assuming a continuous output of 80 amps, that is a total of 160 amps of potential charging. However, the batteries will only accept a fixed number of amps so increasing alternator output charge the batteries any faster. Using 15% as the CAR yields 148 amps so I have no use for larger capacity alternators.
As for the higher acceptance rates of AGMs, they are of no advantage in this regard without alternators capable of delivering more amps. But, as others have noted, alternators in excess of 100 amps require dual drive or serpentine belts. Converting will cost $500 per engine not to mention another $1,000 or more for a higher output alternator. And then you may encounter bracketry challenges.
AGMs are an answer for some situations (difficult access to water batteries, for example) but I see no functional advantage over FLA for most use profiles. Also, AGMs fueled by low-amp internally regulated alternators will be murdered in short order. See Rod Collins' article on his MarineHowTo website for a detailed explanation of why.