Rolls is correct that flooded cells should be charged only at 25% C. On my 440 AH @ 24V system, that means 110 A max charge rate at 28V. The alternator is rated to put out 280 amps @ 28V (I have seen a little higher than that), which is 64% C. When the batteries are low it is replacing over 4 AH per minute (!) into the batteries - you can literally watch it tick up on the AH meter. They will take this rate until they are up to about 75-80% state-of-charge, then it drops back. Yes that would cook Rolls (or any flooded) batteries. Good AGM cells can be charged with no current charge limit - only voltage regulation. When really low they will take 100% C if you can supply it. That makes for a very significant reduction in in engine run times for the purpose of charging, essentially cutting it in half in my system. There is battery plate temperature control on the charge regulator, however another advantage of AGMs is their charge efficiency is significantly higher than flooded cells, so heat buildup during charge has never been a problem - they will get slightly warm to the touch.

I have lots of batteries - in cars, boats, RVs, tractors, motorcycles, industrial lifts, airplanes. I can count about 50 lead acid batteries I own currently in service without trying hard. I have used flooded, AGM, gel, spiral wrap, etc. In my opinion the AGMs are a better product in any use that you can charge them properly. Flooded are only preferred (by me) for installations where they are going to be charge abused - they stand up to it better and are cheaper to replace when wrecked.

Having said all that, they do carry a premium price, and whether it is worth it in an individual case is a balance of cost/benefit. I use a lot of flooded cells because of that. But AGMs have their place.