Who has used personality profiling for senior positions? How useful are they?

They are very useful.
personality & psychometric tests provides us information about knowledge, apptitude, tendencies, preferences, etc.
Skills in leadership, decision-making, time management, etc.
are also provided to give a clear picture of the candidate or the incumbents in senior positions.
Most of these tests are standardized, wherein it can be given to any nationality provided that the instructions are explainded clearly and the test/s is/are administered very well.
These can help us where to place an employee, how many people can he handle, to what extent is his authority and aligning his/her expertise to an assignment where he/she can further succeed for the benefit of the company and the individual.
But don't get the idea that tests are all we need, we need to combine it with the employees track record.

We used to do so and it was Psychometric and personality testing for our mid and senior level positions. This test had been conducted by HR head and she holds expertise in industrial & clinical psychology and it was almost whole day session and some time external expert had been asked for an expert opinion so that best fit candidate could be selected.

We do so the same testing for entry level i.e. for MT position and it was certain reasoning, instant reply and visual based testing but unable to interpret the result as we have expert professionals with such testing.

interpersonal skills are of great bonus for job interviewing and in diverse workplace, however, faking them is a big problem, they should be natural, anyway, they are skills that take you long way not only in ur workplace but in life.