Hi,
djaydino is quite right actually
All PlayMaker actions are pur c# open source codes, so this goes even beyond the ability to use PlayMaker or not within the same project, you can have features that use both at the same time! since you can communiate back and forth between PlayMaker State Machines and regular scripts and Components, so the possibilities are totally open.
However, the actual Finite StateMachine engine is not open source and provided as a dll, something to consider and be aware of.
Typically, PlayMaker is all mighty if you indeed combine it with regular scripts, this is where you'll get the most out of Unity and PlayMaker and totally unleash the potential.
Bye,
Jean