Hi,
I was able to set up the module with NI Reaktor (and also with VCV Rack, CVToolkit, or even Softube Modular) all of them are working fine however with some limitations:

NI Reaktor: yes if i run it as a plug in i can have only 1 input and 1 output to (or through) the DAW (or at least in Ableton).
as Stand-alone i could receive 4 signal and send out 8 signals to Eurorack - so also any ADSR is working fine

My only concern is the latency. I might need a faster computer. Of course in some cases a relative low or middle latency is enough eg some effect etc.
However if you want the same signal coming into the software and going out to Modular again then this means every in and out on the same signal route will add latency - so at the end you might end up summing up a lot of latencies. Plus also in case of using software VCA (or LPG) with Hardware VCO if the attack time is fast then i can notice a strange sound at the beginning of each note i play...

I saw that it is possible for a Plugin to use multiple channels to Ableton. like Softube modular can route 4 auxilary outputs to Ableton. These outputs you will be able to select as an input for a seperate Ableton track. Would be nice to have the same for NI Reaktor. And would be even nicer to have an option for multiple INs and OUTs as well.

Or another solution could be if you could use direct access to the soundcard not only in stand alone mode but also as a plugin.

I like the possiblity in VCV Rack that you can add 2 (or more)Ö out modules and will be able to select different soundcards for each OUT.
So you dont need to make aggregate devices (in OSX) but can route Inputs ond OUTputs to different places at the same time: eg: to ES-8 for CV plus to DAW or another soundcard for recording audio or listening through headphones etc..

"MrWigglesworth" just send me a message with details and i can help to set up Reaktor ADSR with ES-8 (in standalone mode) if you want.