This is from a different perspective...

My husband is a T (he is trained as a T, but at this point in his career is not doing much counseling and is doing more administrative work). He has never been in therapy himself. I am in therapy, and it is clear that he does not understand what it is like to be on the client side of therapy. He doesn't fully understand the feelings and issues that clients can have toward their therapists, etc. It isn't that he's not caring or compassionate - he is - but I think that never having experienced therapy as a client himself really limits his perspective and understanding of what clients experience. I fully believe that Ts that have experienced personal therapy have an advantage over those who haven't. I don't know that it makes them a more effective T in terms of technique or theory, but I do believe that it helps them to understand the client experience more clearly.