I haven't ridden it in two months since the frame broke, but I had the XRF8w in my Downtube 8H (it replaced the original non-W).

It was somewhat noisy in gear 4, and 6 if I remember correctly, and a little less so in 5,7,8.
Since it was direct drive in gear 1 and various combinations of 1/2/3 sets of gears in the other speeds, I presumed it was just normal mechanical noise. I had about 3000 miles on the gear.