Xantrex 1055 manualAssuming you are on AGM battery charge setting with 14.3 charging and 13.4 float. This seems low but I don't have the specs for Full River AGM. Probably 14.6 to 14.8 volts would be better and can be set using the custom battery option. I might go .1 high on the charge and .1 low on the float (vs spec) while off grid. Then the 9245 when plugged in.
Otherwise yes the 9245 converter together with the 1055 will charge faster.
on edit:
fullriver specsLooks like 14.7 & 13.7 so I would set the 1055 to 14.8 and 13.6 for off grid.