I have a Xantrex inverter/charger (model RS2000) which boiled flooded cell batteries no matter what settings I used. I switched to AGMs a coupla months ago and its charge algorithms are different for AGM; it seems to be treating them well so far.
For long storage periods a charger w/a low-ish top end charge rate should provide some safety factor against abuse of the batteries. I use
this one in my garage where I switch between a coupla spare flooded batteries, which it has kept in excellent shape for a remarkable time. I took a small tractor battery out of the over-the-hill tractor over three years ago, and that battery is still working fine (it was over a year old when I took it out). I believe the Griot's unit is
made by this brand as the features are similar; Griot's has selections for AGM batteries and for 6V, both of which I have used (I charge two spare 6V AGMs which I bought cuz they were crazy stupid cheap). The Griots unit has a 3.5A charge rate which is high enough to handle some real charging but not so high as to cook large batteries (unless you put them to bed w/out enough water to cover the plates).