Hi MG,
Wow! Your are one great artist, MG! I found myself having to go back and continue listening to your various movements. I could not identify any specific familiarity in "The Echos", except that I could not get Scott Joplin out of my mind. I don't think you have any worries about duplicating someone else's efforts. The familiarity ends with the style, not a specific song. If there are any similarities, it seems they are your own. I often have that feeling of familiarity and I find myself raising a 4th, 5th or 6th just to try and change the direction. I don't see a problem including the piano in that movement. I really like everything I've heard. Your music is awesome!
Fred