I think the difference between DWC and SWC is just the size of the tote. So it can be a volume difference and perhaps a 'heating up' difference.
I aso have never heard of 2 root systems. For sure a plant develops a different kind of root system depending on the medium or the way you give them water.
What I did see with systems where there is a large gap between the watersurface and the bottom of the netpot is this thick, almost woodlike root. Totally useless for the plants or the roots, and thus a waste of space.
Most hydro-sytems are very alike. It are just small changes, hybrids or modifications.
For sure there are differences, but lets not make things to complicated.
Look at the 'Kratky' method: Amazingly simple and it works as well.
Also be aware of anecdotical evidence: I have seen respected members here talking about why their system is superior because since they changed the system, they never had root rot anymore or their yield got better. I am happy for them, but perhaps they just became better growers.