maybe you should blur your AO output to avoid that grainy look.
Or raise the ray samples, but that’s gonna be longer 
Yes, it’s already as long enough ^^ I’ll make a bit of PS next time 
Anyway, I’ve added a new algorithm to the raytracer. A simili Path Tracer that take longer, but could give really cool results like this:
(This one with not enough passes)
and these, one with some colour in the cornel box…
A
B
scene quickly made in blender and imported into JME3 then raytraced.
neat!