It would depend on how afraid he is. If he's just doing a lot of avoidance behaviors (ducking head, crouching, hiding behind you, etc) then yes, if I trusted the groomer, I would. The groomer should be able to handle that by being calm and gentle. I might even pay for a double session so that the groomer can take as much time as necessary to make your dog as comfortable as possible.
If he's showing any signs of extreme stress (shaking, drooling, any defensiveness, etc), then no, I would want to ease into it. Short visits, maybe have the groomer brush him a bit while you're with him until he calms down.