Don't know the benefit. Here's two risks.
First, the girl will be in your place. So, worry about neighbors, her knowing where you live if a problem develops, her knowing what you own, etc.
Second risk, is it's much harder to send the girl away if you don't like how she looks or what she's like than it would be for you to just up and leave her place. Also, she may have a driver sitting in his car outside your front door.
As to price, from the ads I've seen, outcalls are similarly priced as incalls for the hour rate. You usually will not find SS or HH rates for outcalls, so that's another downside.