If you have to take your dog to be groomed, I wouldn't consider leaving it at all. I would insist on watching EVERY part of the process. Ellie is groomed at home and has never been to a groomer. She never will go to a groomer either.
There are way too many horror stories. I tried using clippers on her once but I made her bald in a tiny spot and she hated them. She has a cottony coat that doesn't part down the middle so her hair is wild. I just use scissors and cut her that way. It takes about 2 hours every 2 months but who cares. She is worth it. There is too much of a chance of something going wrong when you take them to a groomer. Some groomers use drying cages incorrectly (I think all use is incorrect actually), they are put in a noose and if the groomer turns the dog could jump and get strangled, some people hit uncontrollable dogs. It is just not worth it.