Is he Alan Burdis or John Gay? They both are excellent UK growers using this kind of setup....
It is working perfectly well, providing the irrigation water is properly monitored, fertilizer, buffering capacity, pH... Now if the setup stops working for a day, the roots will not be in the best possible condition, and the plants can eventually collapse. I used something similar before, with a daily watering schedule for rothschildianum seedlings, they did great, but you cannot let them dry out.
Rockwool is used for this kind of continuous irrigation, because it supposedly does not break down ( but it is too inert, there are spines and needles that bruise the plants, etc, etc...). In theory, anything can be used for continuous irrigation, as long as it is either stable, or the decomposition products are easy to flush. I saw in Malaysia beautiful lawrenceanum, dayanum, and bullenianum in chinese sphagnum moss, watered daily. However, if they dry out, the roots will die pretty quickly. Another thing, in case of pythium, phytophthora, or a couple other things, they can be devastating in no time in such a setup.