I have not been involved in this as a harpist. Diane Bish made a wonderful CD with Susanne Macdonald of popular hymn arrangements. I have been an organist and pianist for over 35 years. Ensemble playing demands sensitivity to all the musicians in the ensemble. Harp can be paired with piano and organ, but you are correct in saying you do not want the harp drowned out. Last year I played the piano with a small orchestra for a Christmas cantata at church. We also hired a harpist as part of the orchestra. I had to make sure the piano part did not double the harp part, so that the harp’s counterpoint could be heard.