Hun--
I'd give wi/wo a go. I don't think there's a right answer, but, even from a PD point of view, if he's not crying, you're supposed to leave, so to do PD right, you'd basically be doing wi/wo.
The other option is gradual removal--stay in the room in chair until he's a sleep, gradually moving closer to the door over the course of several nights.
However, if he was at one time an independent sleeper and this is just a blip, I'd try wi/wo.