HI Marc
I have both the Lab 9s and the Lab 5s , in different rooms
They are both excellent but do have quite different sound quality... and price tags
I have been surprised by the quality of the 9s and did audition them in my room with the 3s before I committed. I would have to say that the 9s are in a different league from the 3s and I personally feel that the price difference is justified.
If you can stretch it the 9s are a re much better speaker and have simply delightful and very powerful bass