The metamaterial tweeter absorber is great as a scientific research result and proof of concept (and also for marketing) but is probably one of the least audible improvements of the latest KEF innovations/evolutions, I wouldn't really miss it thus on the LSX (I own both generations of LS50) if all other driver, electronics and usability aspects are improved (hope there will be soon some measurements and white paper). Possibly they didn't use it also for product series hierarchy reasons.
The 12th gen. UniQ has some extra changes beyond the metamaterial. I can see the logic of not including them due to the relatively lower amount of spl an LSX can produce (less power, less resonance), but stil...
I agree the key aspect is the connectivity improvement, and if it´s analogous to the LS50WII, that is an automatic win. These speakers are one of the best options for a compact set for a PC or for small rooms. My veredict is the same as the LS50WII: if Kef implements Dirac (or any other good EQ software like Audyssey) on these sets, they can effectively get a killer product.
And finally, since this is a Kef-specific thread, I´ll abuse your patience for a little personal story. I started with serious audio getting a set of Kef Cresta speakers. Eventually, I moved up to my current, second hand set of IQ´s. A week ago, I got a set of LS50WII for my mother, as she enjoys audio a lot all day long: she watches series on tv, listens to the radio and listens to music while reading. To me, the set is a perfectly rounded, all terrain system. I has not let me down: it sounds incredible and with the KC62 on a small room, it destroys any soundbar and produces a clear, clean and well-articulated sound.
I have been able to finally listen to a set of R series. I have noticed that they are not a revolution, but an evolution of my IQ series: they sound quite similar but doing everything the IQ better: more linear, more SPL, more dynamic range and a very, very similar dispersion pattern. However, with some work on the IQs and positioning, I think I can make my IQs sound if not as good, at least, close enough.
I have been wanting to upgrade the whole rig, but after listening to Kef actives and the more recent passives, I´m not sure at all what should be the next step. Better room eq (and hence, electronics, as the IQ´s run on a Denon AVR 2808 from around 2007) or ditch the whole thing hoping that Kef will come up with an active surround set based on the LSX/LS50WII/LS60? With better electronics, it would still be possible to stay passive but upgrade in the future. Worst case, I can always substitute the PSW2500 for KS92´s, which effectively are four times more power in amp terms...
What are your forecasts, guys?