Lance,
It just depends on the specific lease-option contract. You can sometimes find a desperate seller who is willing to allow you to "buy" their property with terms that are actually causing them to lose money. An example of such a deal would be that you might have a lease payment equal to their mortgage payment and they pay taxes, insurance, capital expenses and maintenance. In this case, if you were to rent the property, someone else would be paying a significant part of your expenses for you and they will lose a LOT OF MONEY.
On the other hand, if the owner sells the property to you so that they will make money, then you would have the normal 50% expenses and a higher lease payment than their debt payment, meaning that you would be paying MORE (and making less) than simply buying a similar rental.
So, the answer is that "it depends".
Mike