I dont do DWC but i do hempy, but i germ in 2" Grodan rockwool cubes. I plant seed directly into cube, and once it pops above ground, its taproot still hasnt made it out of the cube yet. I will transplant then to my hempy buckets. My thoughts are: If the roots "dont know that they are being transplanted" because they havent made it outside of the cube, then how will they be stunted? All the little seedling really notices is a light change. But that is my experience and thoughts only. Anybody else want to chime in on this method?