I dunno. I personally enjoy this as it is without a singer. I mean, depending on what is sung and who the singer is could really change my mind. I really love how the piano and guitar weave together so well. I didn't think it was very jazzy except for a few stings with the piano that get especially prominent towards the end. It sounds more like a pop ballad or something. Anyways, great song and your production, I think, is actually very good!