Hi Graham,
I have the same itch about the multi-way horn that I have started to scratch. 5-ways but in wood the whole way - this is clearly a big project and a lot of work but I am making good progress. Personally the multi-way horn system is imho the ultimate solution but also the easiest to cock up big time - I think it requires dedication, time and skill to get right. DSP based crossovers have made the *Objective* promise the fix this issue but I haven’t heard a pure dsp multi-way that doesn’t lose out somewhere. I think a hybrid dsp solution has much more chance and one I think can work as I have tried it a lot. There are some significant advantages (on paper) to FIR based crossover filters and a means to correct badly behaved bass in normal rooms. I am working on this right now as an alternative solution for non-purists.
Uni, Cessaro and Kodomo’s all share one thing in common - compression drivers with Be diaphragms. Uni and Kodomo both using Radian Be (amongst others since Kodomo’s is a more complex system with 5 channels I believe). Cessaros using TAD Beryllium.
Personally I think the Radians are a kind of no brainer driver due to very favourable price: performance ratio. TADs are obviously known to be king of the hill in the beryllium world but much more expensive. I think Kodomo tried TAD but stuck with Radian. I think the recent uni videos show a speaker with well integrated drivers and plenty of fidelity and insight. I think the choice of JMLC mid and Radian makes an awful lot of sense. The new reference uni 4 way coming out soon will be interesting because that will go much lower than the normal uni and has a full front firing mid bass horn so much less compromised. In terms of Cessaro - I have only heard them at shows where, being honest with you, I shrugged my shoulders as they always sounded poor. A show is a show though and I am sure like with everything else, they can be made to sound good in the right hands. I have enjoyed Tang’s journey and think his latest videos have got really good with the sub integration sorted. The Bruckner one especially sounded great.
In terms of horns voicing , my personal taste is more bottom up than top down. I prefer a big weighty mid bass anchor. I also have a serious soft spot for quite a lot of the vintage horns and their drivers.