I don't have a 95x to directly compare to, and I sold my 6xx when I got my beyerdynamic T1.
In my opinion, the Ribbon is far better than the T1 for listening to music.
It's probably got the strongest bass I've ever heard on an open back headphone. I mentioned it in a previous comment, but when the bass is particularly strong, I can actually feel a 'breeze', from the large amplitude motion of the driver.
The treble is also really good, no obvious spikes or drops like the T1 has.
The only place the T1 wins in music, is very rarely in male vocals. Sometimes, I feel like male singers feel 'far away' and their voices recessed on the ribbon, whereas they'd consistently sound great and nearby on the T1. The odd thing is that this is hard to replicate. I could be listening to "Fear of the dark", by iron maiden, and the Ribbon would sound just fine with the male vocals. Then I'd listen to "No More lies", and the very same singer suddenly sounds as if he's singing from 'far away'.
Could it be because there is some difference in the songs that the T1 can't capture, which makes the T1 sound more consistent to me, whereas the Ribbon can capture the differences which makes things sound worse? I don't know.
I'm interested by your comment about congestion in more complex pieces due to the bass. I can't put my finger on it, but I feel like I've personally also heard some weird stuff in complex songs with a powerful underlying bass. Could you link to some the reviews you've read saying this? Strong bass electronic music sounds great, but sometimes when they've got a high frequency piano notes played simultaneously, things start to sound weird in ways I don't think I can properly characterize yet (it's almost as if the piano notes played, which should have no volume variance in time on my T1, sound like they have volume fluctuations of the same frequency as the underlying bass). When heavy bass is being played, I can physically see the driver moving back and forth. Could it be that when strong bass is played alongside other things, the large movements of the ribbon driver for the bass causes the sound source location for the higher frequency components to slightly change? I don't know, but want to find out. I would like to look for more applicable music samples to better understand what's going on.
I think it's too early for me to truly give a review of these headphones. I'm finding now that I get what I paid for in the speaker amplifier I cheaply built - when I turn it on, it starts out fine, but as time goes on the amplifier starts making weird crackling and whining noises at high volume, and it also readily shuts down from clipping problems the second I go past ~70% amp volume. I'm impressed enough by the performance of these headphones, even through the amplifier and power supply noise problems, that I've already placed orders for higher quality and more reliable amps and power supplies, to hopefully drive these off of cleaner and more reliable power.
While I think it's too early to truly review these, I can say that so far, they sound far better for music than the beyerdynamic T1. If I ever start up my computer with the intention of playing music, I won't even consider using the T1 over these, even with all the current amplifier noise problems.
Would I want to wear these for a long time given the current pads? While they are far lighter than the T1, the current pads make them annoying to use for a long time.
Also, the strong bass makes these too 'boomy' and distracting for playing video games, so I find myself switching to the T1, which also has far superior imaging, whenever I want to play FPS games.
In listening to music, I sold my 6xx because I liked the T1 so much, and so far I strongly prefer the Ribbon to the T1.
Unfortunately, I don't think it's fair to say that headphone quality has a true 'order', so even though to me T1 > 6xx and Ribbon > T1, I can't guarantee that I'd have found the ribbon > 6xx, but off of my memory of the 6xx, I'd claim that the Ribbon > 6xx. That said, until I choose to get another 6xx, I can't directly and fairly compare.