search the forum for some info on the Cimaf. I can tell you that the 870 is not at the top of the pack for hydraulic performance but the performance is matched to the horsepower.
If you don't need the extra weight of the 800 series, the 770's are virtually identical. They share the same motor and a lot of other components but the 870 is quite a bit heavier and you get like .5 gpm more IF the machine is exactly within specs.