I've worked as a groomer for 3 years, it's important I think to go check the place out, see what sort of equipment they use, ask if the dogs are kept in cages or let out to play, meet the person grooming and have a chat, you can usually work out the dog lovers to those who just do it as a job.
There are some dodgy groomers out there but lots of them are dog people,they have there own puppys at home and do the job because they love working with animals.
It takes me 2-2.5 hours to fully clip a cav, trim feet, trim nails, clean ears etc.
I have dogs stay with me all day, mostly they stay for 3-4 hours but that's because i work on my own so i usually do two dogs (clip one then as its being blodryed start another), however if someone wants to get there dog asap we just arrange that, that dog is to be done first and I call them the moment its ready. I have also had people come and stay for the first few grooms so the owners can see what's being done and what the dogs do during the day (which is a dog play session usually around my feet as i try and groom).
For first time grooms I usually have them stay a few hours as I groom them in 10-15min bursts, i find it better to groom them gradually so the experience if fun not scary, this gives them time to get used to the noises in the grooming room, and some play time with the other dogs.
Cav's nails are really really good!!!!! Hardly any cavs seem to have black nails so you can easily see the quick, as for dogs falling off the table, most groomers secure the dog to the table so this can't happen.
If in the end you just can't stand leaving you pup at the groomers i would suggest finding someone who does home grooming, have them come to you so you can be there (only problem is the fur will go everywhere :lol: )
Anyway, don't stress to much!! All groomers arn't scary :lol: