I have split the spanish right through the center of the iberian pennisula and havent seen any problems with riots or revolts in there provinces. I'm retraining and regrouping for my final push as this will eliminate the spanish who have been kicking my behind on the seas. On the other hand I have noticed an significantly higher amount of roaming rebell armies of decent size (1/2 and 2/3 stacks) which seems to have worked in the spanish favor as these rebel armies stand on paths to the remaining 4 spanish cities but dont seem to be attacking them.