Once you decide which batteries you are going to buy you need to make sure your charger will be able to charge them. My Xantrex can handle 2 banks and I can switch the charger so one bank is for AGM. I would not want to switch to both when plugged into shore power as I would ruin the batteries. If you are going with the AGM's than you might want to get a smart charger with a Link 10 or 20.
Good luck with the batteries and the charger.
Ken
AGM batteries typically have the same charging profile as flooded cell batteries. You have to be careful because some of the battery charger companies have put the "AGM" setting to charge like a gel battery and it will shorten their life. AGM's are not gel. It's a good idea to look at the charger's manual and see what the "AGM" setting is actually doing and compare that to what the battery manufacturer recommends.
Your altenators are set up to charge flooded cell batteries so that's why I wonder what the deal is with the charger companies basically putting in a switch for "AGM" since it should basically be the same as flooded cell... maybe it makes people feel better or something.
If you have an older smart charger for flooded cell batteries, it'll probably give you the correct charging profile and there is no reason to run out and buy a charger just because it has an "AGM" switch. Buy a few cases of beer instead... better investment.