I’d say the hiss is reduced. The 3rd Gen feels like a genuine upgrade. 

Just got mine today and on the plus side, they quickly turn on, there is no bluetooth noise when you turn them off and they has a much better battery life. They have much more base and It's not uncontrolled in anyway, the bass is just more in focus, especially the higher bass frequencies :/ But they really lack a lot of treble, especially if you are coming from a pair of H9i where every detail in that area is so overwhelming. Personally, I think they have got a more stable and clean frequency response in the area, as according to this link H9i https://www.rtings.com/headphones/1-2/graph#813/2050 might seem to have some problems with, which also can be the the reason to way the sound was so sharp in some songs. 

Is it just me or do they sound very if not extremely thin in the treble area compared to the old H9i, that with some songs could be a little too much and even with a little sibilants on higher volume?

leosgonewild wrote:

I went to listen to these today. 21 seconds was all I needed (what song I should not have to mention). The sibiliance issue is still there. It is slightly reduced in one way, but worse in another way. It has basically just changed.

I miss a bit my old H9i. Although the treble on them was not particularly flat, they were insanely detailed and open in there sound signatur, the bass was tight and controlled <3 I just miss them.