And it gives more control than a single-ended dildo, too.
The big thing is to make sure that the harness has a hole in the pad or the pad is removable, and it can be worn down low enough (most decent O-ring harnesses can do both of these). The low position is important for her pleasure in any case, as it ensures that the base of the dildo can rub against her clit and labia with each thrust.
The Nexus can also be a good choice. Nexus Max and Feeldoe are the two vibrating doubles (with the sad, and hopefully temporary, absence of the Tango)