Dose carefully and limited especially with synthetic cannabinoids, since it is easier to OD on them (well especially in pure form) than actual cannabis and this could lead to such things as panic and rapid heartrate / palpitations. Since 6-APB is a stimulant that can be all the more uncomfortable, along the lines of subjective overstimulation.
If you are modest with dosing the cannabinoid it should be fine and I don't mean to overdramatize, but make no mistake... a number of these synthetic cannabinoids can be rather scary with overdoses, both psychologically as well as in terms of seizures and stuff.
And combinations are as a rule less predictable.