tsvisser, I guess every user would want a new product to lean more to their style of workflow, but I think whether a product will sell or not depends a lot on the positioning or it's target market, and how much they are willing to pay for the feature set.
Here is how I see the 3 similar products I mentioned:
The Studiolive is a digital mixer. It boasts its DSP for digital effects (including compressors) for every channel. Personally, other than live purposes, I don't see any advantage of having a digital mixer to mixdown recordings nowadays, especially if it doesn't have motorised fader (left out due to the price). Why would anyone want to route streams from the computer back into a digital mixer to mix with its proprietary onboard fx eludes me

, especially nowadays DAW plugins are getting more and better by the day, many high quality ones are priced very low (sub $50)
The N12's eq, compressor and reverb are also digital, but it has only 8 pres. It boasts the "one function per knob" integration with Cubase AI, very deep integration that even lets you control the metronome level from a knob. It returns from DAW the same number of channels it can record to it. But again hardware mixing's appeal is questionable since it is a digital mixer. But the clear selling point is integration with Cubase AI.
The Onyx 1640 is arguably the closest in form to the Zed, with 16 pres and analog EQ. But its workflow is more leaning towards using it as a tracking mixer, then mix/sum ITB, given that it only can return 2 channels playback from DAW, a feature (or lack thereof) which made me scratch my head when the product was released. But of course they keep harping on the quality of their pres and eqs...
So where does the Zed R-16 stand? The thing that gets me excited is it does 18 in and 18 out to and from DAW (plus additional ADAT streams in certain sample rates). I am still not so sure what its MIDI ctrl is capable of doing as tactile control, but to me that does not affect it's positioning. Because it addresses squarely the wish for people who wish to use a mixing board as an analog tracking and mixing platform, and yet have the DAW for a recording "medium", plugins for efx and ITB automation. It is very clearly appealing to those who wants the cake and eat it, like me

I get ITB recallability and micro accuracy in tweaking and automation, yet I can pass it through an analog board to use outboard fx, analog eq and analog summing and record it back again through the master buss. And I think A&H cleverly designed it with serious project studios (read: those which actually rents out its rooms by hour, albeit at a budget price point) in mind by rounding up with the most important feature: its looks and size.
No offence to the other 3 manufacturers or the capability of their products, but if you place those other 3 products in a project studio, your clients will perceive your place as a home studio trying to make some side income. But if you place the Zed R16 as the centrepiece in your ctrl room, given its size, look and brand reputation, people will get the impression it is a serious mid budget setup maintained to offer recording services. It's that obvious to me
Add some nice affordable outboard pieces and some preamps via ext ADC and ADAT and you have a winner. The rest of the features are just (very nice) icing on the cake IMO
(no, I don't work for them)