The Progressive Dynamics 9200 Series Converter/Chargers are smart chargers with four stage charging. According to the Progressive Dynamics brochure they are available for Lead-Acid or AGM batteries. However, the brochure is dated in 2018. To be sure, call Progressive Dynamics and ask. They do not appear to be temperature compensated. That means that in hot weather or cold weather the PD9200 will overcharge and undercharge the batteries. In my opinion, while parked in a RV park and on shore power and using 12 volt lights and appliances, that will not make a big difference. However, when in long term storage and on shore power, it will overtime degrade the batteries. For that reason, when in long term storage either (1) turn off the charger and disconnect the batteries or (2) turn off the charger and connect the batteries to an external battery maintainer/charger that has an AGM setting and is temperature compensated.
As for what batteries to purchase, I would recommend Group 27 AGM batteries. Almost all available Group 27 AGM batteries will be a direct replacement for the batteries you now have.