I do not find the AGM's at all "fussy"..Indeed, they are likely to keep on going in circumstances where wet cell would boil off and curl up their little leaden toes.
A classical example of this for us was with a starter battery. The ignition switch failed in a special and unhappy way, in that it kept feeding power to the starter motor even after the you let go of the key. Not enough power to crank the motor, but enough to keep the solenoid engaged. So the starter motor was acting like some deranged unregulated generator that fed back into the battery....
By the time that all of this was discovered, the starter was toast...and the AGM battery was doing its best to look spherical. I kid you not , the casing had literally inflated, the only thing holding it "in" were the battery clamps...which made for an interesting shape once everything was removed for repair. The thing is, the battery STILL works. It looks decidedly odd, and we have taken it out of the boat, but it did not burst or leak and is currently doing sterling service as the battery of my 4wheel drive. It has been doing this for a little over four motnhs now with no problems at all.
So I will stick with the "finisky" AGM's and also tell people to watch out for "peculiar" and expensive little electrical glitches with their boat starter systems. I had a couple of small salt crystals, inside a $14ignition switch do a little over $900 of damage in 15 hours of motoring.
I love sailing, don't you?