Let first say that I don't care what type of battery people what to use on THEIR boat and don't understand why so many seem to. So many batteries choice threads are people looking to prove their decision was correct to justify whatever it was. Get the batteries you like and move along.AGM take charge more quickly than wet.
Never require constant filling with DISTILLED water ( hidden expense and again time and effort) AGM you don't sorry about battery acid leaking.
But far as charge acceptance
- except a fairly highly discharged battery the acceptance of AGM is not much a plus. I wonder just how often AGM owners ever put in more than 25% as current/20 hr capacity into their batteries??? I bet most don't even have a charge source that could.
- I water my FLA batteries 1/month and it takes about 10 minutes. The 4 of them normally take about 2 cups of water. That probably works out to about $0.50/mo. I wouldn't call that "constant filling" or much of a hidden expense
- I never have ever worried about my batteries acid "leaking"
If you want to use agm, gels, lithium, or whatever batteries on YOUR boat go ahead. They are just batteries, they are met to be used, abused, and replaced when needed.