Reading the spec, an AC modem vs a AX that only have bgn on 2.4ghz, is pretty much the same. Am I reading this right?
AX on 5ghz only, only adds some enterprise auth requirements. Then there's the debate if OFDMA is even better than OFDM if you are not adding dozens or hundreds of clients. I'm not. Mimo part is literally the same between ac/ax (5/6/6e) if you exclude OFDMA tradeoffs for more stations.
There's very little actual info on this topic. I'm a software person like most people in this forum, we care about the driver enabling the feature or not And things like wikipedia are full bold claims about clear superiority of wifi6 but only have references from zdnet
(in the end, i'm just trying to chose between a E5600 AC with proven chipset, or a RT3200 with broken single-channel AX and unproven chipsets )
802.11ax radios do provide real improvements for 2.4 GHz. How much in practice is hard to tell, as it depends massively on your environment (interference, channel utilization, number of neighbours trying to compete with you).
Just to quote the (rather meaningless) marketing blurb, 802.11ac may give you a (theoretical, brutto-) link data rate of 300 MBit/s, while 802.11ax might provide you with a (theoretical, brutto-) link data rate of 1'200 MBit/s. No, you will never actually achieve either of those values in practice (and the number of rx/ tx chains supported by your router and your clients, as well as its spatial orientation relative to your other clients play a big role), so these values are indeed purely theoretical.
is BSS Coloring even relevant with a single AP? I just clumped it under the "enterprise" features of AX I won't need when reading the spec.
Also, i couldn't see much changes to how 2.4 is used if the router doesn't implement AX on the 2.4Ghz, which is pretty much every single modem available today at non-"gamer price", and the reason i'm starting this thread. I am fully aware 2.4Ghz with AX support is very desirable, but we can't get it yet, so i'm raising the question, is 5ghz-only-ax even worth the trouble of having a less supported device?
I might have read it wrong, but BSSC is a mesh protocol component. wont' help at all without all base stations cooperating. Only relevant in practice at large scale (and dense) deployments, think things like huge company campuses or stadiums.
And even if I read the spec wrong and it is useful in a non-coordinate mesh, good luck living in a place where the whole building is made up of rich gamers or network enthusiast otherwise all you can do alone is to dodge crowded frequencies, but that is pretty standard even in the ancient revisions and BSSC (or anything added on AX) doesn't improve that.
Hmm, as far as I know, it's not a mesh feature at all.
But what is important is BSS collision detection and then resolving it.
ath11k, for example, has an FW feature to detect it and that's then propagated down to hostapd which will start CCA and randomly pick a new one.
Just that alone really helps, the downside is that there are only 63 combinations.
You cant really look at it that way, cause by that logic whats the purpose of new 802.11 revisions.
I think you are correct, but that is not the "coloring" part. What you described is usual collision detection. It's not new to AX.
The "coloring" part is just a way to document in the mesh which frequency collision can be stepped over to avoid stepping over something that might be closer to you and cause worse damage.
A mesh can have AP A, B and C. it knows that A and B are very close and C is far away. So if B is stepping over C (which now is transmitting at high power), it might change frequencies and step over A (which is now idle). but with coloring it won't do that, because it know it is not really impacting C which is far away, and will prevent future conflict problems with A.
I have Xiaomi AX3600 and AX9000 currently.
I have not tested b/g/n at all, there is no point in even testing as it's just 2x2 2.4G, it cannot provide better performance without AX
And things like wikipedia are full bold claims about clear superiority of wifi6 but only have references from zdnet 
)
otherwise all you can do alone is to dodge crowded frequencies, but that is pretty standard even in the ancient revisions and BSSC (or anything added on AX) doesn't improve that.