The powermaxes, once they get the battery to 14.6v, assuming short thick wiring, drop to 13.x something or other and the 85% to 100% stage takes probably 24 hours or more.
The PD9245 might not do Trojan's recommended 14.8v, but it will hold 14.4v for 4 hours when asked to do so. With the PM, one is powerless to hold higher voltages when desirable.
If generator charging day after day is in your schedule, the 4 hours of PD's 14.4v will return the battery to a higher SOC than the PM's 14.6v, and battery capacity will walk down less fast.
As far as combining with other charging sources, Once the battery voltage gets to the maximum abosrption voltage of one device, it will drop out as the other takes over and raises the battery voltage to its maximum.
Yes charging sources can confuse each other when batteries get in the 80% charged range or higher, but usually work together well below that state of charge.