We have worked with many interior designers on various projects and it rarely ended up with the best possible result! unless there is a close relationship between architect and the interior designer, involving a second designer to work on someone else's creation is a risky move.
Most of the time the interior designers don't follow the architect's idea and won't stay loyal to the original design concept. As the result the potentials of the design won't be fulfilled and the best possible result won't be accomplished.
Same has happened for many of our projects such as Hillhurst, Jonhston, St Ives ... (although they were still among the top but in our opinion not the best they potentially could be). That's why we decided to do the interior design of our projects by ourselves to make sure that what we have envisioned is fulfilled and a consistent integrated idea/concept is followed through the whole project.