Tracey
I don't see how it's more work for the SP. If I were to "put myself in the girl's shoes", I'd prefer MSOG with breaks than getting pounded for an hour.
The no-MSOG policy only benefits the SP who can obtain a quick release and leave early. In fact, the policy may be an incentive for the SP to do just that. That is definitely not what your clients want.
No doubt you get repeat business, but the real question is how many customers do not repeat? As they say, for every customer that states a complaint, dozens more act quietly directing their business elsewhere. If you don't listen to your clients, an new agency may.
At least consider our input. Talk to other clients and agenices before locking-in your position. Also look at trends. I'm sure everyone here would appreciate you taking more time to reflect on this.