I am not familiar with either one of them but I have a few thoughts anyway (wish more people would start their post that way).
Can you tell the difference between them sonicly? I'm sure you know there is the camp that says "digital is just 1s and 0s" and thus you should not get any improved performance from any streamer. I am of the opinon that the differnce is minute and frankly I'm in the process of trying to figure out what a streamer, either expensive or iniexpensive, would improve for me. So your post is nice to see.
I agree that you should definitely move on from the Bryston. Whether you should stay with the Yamaha depends on if there is any difference in the sound and if there is anything that could be had from an upgrade (to something besides the Bryston).
I always consider it a win when you find a basic peice of equipment that performs well.
Good luck,
Jerry