Marko-2 things-the batteries are judged on Reserve Capacity. the Firefly carbon foam did not exist in 2015 when the northstar was being installed. If you notice the reserve capacity for the Northstar is the best except for the newer chemical carbon foam which was introduced later.
reserve capacity is a measure of High surge energy draw which these batteries meet.
there is no question in a low amp situation-say 10 amps max for fridge and fan and those kind of things-the thicker agm works well. it is not as fast recharging as tppl and not as efficient discharging.
it's an apple and orange situation