Have not looked at the Gate 1 Africa, but will tell you we went to Botswana last year with 2afrika.com
Their prices are up from the special we got, but I would have to say we had a good time. Good service all around. Maybe you want to take a look at them.
With them you have the option of extending out your return date, which we did and then booked a walking safari for a week out of Johannesburg. That was really good. Only 8 people, two different tent camps on a private reserve.