I have not flown on the Boeing 787-9 nor the 787-10 as you have had the chance to, very cool to hear about your experience and you are quite lucky too since I don’t have a easy time finding any airline flying the 78X near my country.
But as for the 787-8, which one version, a member of the 787-family that I have indeed flown 3 times on both medium hauls and long hauls.
I flew with Qatar Airways and all three flights were very smooth, very quiet and the fact that the 787 tilts at a ever-so-slightly higher pitch is actually if you look very very carefully visible, which is pretty cool since you can’t feel the pitch, but it really makes you feel like you are gliding though the sky as a plane does. I also got a bit lucky having almost half the plane for myself considering it was very empty on two occasions so I was just laying across all three economy seats which by the way was very soft and comfortable to sit on. Legroom, now on Qatar that is, is actually pretty good.
So all in all, only the plane itself is magnificent aircraft that gives you a comfortable flight to enjoy and too remember a life-time out. I would love to get the chance to fly on -9 and -10 in the future :)