It can be a great idea. I work Saturdays at a shop that runs that way. The owner is a groomer, and originally did all the grooming. Now, she does much more customer service, the bathing and prep work, and retail rather than grooming. She can and still does in a pinch, but the rest keeps her busy enough.
As for finding an employee that is loyal? There's no guarantee, in any business really. There are things you can protect, like client records. An employee really does not need access to addresses and phone numbers. Those are easily found in the phone book if they really want them though. If you are doing the prep work, you can choose to keep your prep products sort of secret. The prep is the key to a great groom.
The reality of having employees is that rarely do they stay forever. At some point, in everyone's life, you switch jobs. It could be because of a move, a better offer, any number of reasons. I have worked in 6 salons in my career. I am currently still working in 3 of them. While I never copied client records, many clients followed me. I didn't seek them out, it just happens. At this point I can not imagine ever leaving the clinic, but I can't see the future. Who knows, maybe someone offers me a deal I can't pass up? Maybe the practice gets sold to someone and I no longer care for how it's managed?
As hard as it is, as a business owner, you always have to be prepared that employees do not have the personal attachment to the business that you do. Clients are only as loyal as what is convenient for them. They do not have that same attachment. They drop their dog off to us every 6 weeks, and pick them back up a few hours later. While WE spend time caring for and getting attached to their dog, they only see us for a few minutes at drop off and pick up. It's not the same relationship. Personally, I am not with the same hair dresser I was 10 years ago. People move on, find other businesses that for whatever reason suit them better.