Time at charge should be a consideration. With a 36-ampere Megawatt I can arrive at a fully recovered group 31 in 1 hour 48 minutes. I do not have a group 31-flooded battery to compare it to.
Phrased correctly an inquiry to Concorde's tech assistance would render a more comprehensive answer. Apply 14.4 volts absorbsion voltage to each and how long would it take or what is the Delta T (differential) time to achieve 100% state of charge in a 100 amp hour AGM versus a 100 ampere hour flooded deep cycle battery.
100% SOC should be emphasized, as should the point of 14.4 volts being achieved instantly at start of charging.