Have never done dwc as it just did not lend itself well to micro growing if i grew bigger that would be a different scenario. As for the past, peat based mixes, to nice organic composts mixes, vermiculite stuff but more for cloning, perlite a little but branched more into higher concentration mixes of it with peat and or coco. Obviously coco as well and that being my favorite but have used from commercial bagged quality stuff to $1 bricks and pet store coco, guess hydroton as of late to that well for me anyways as i saw quite a few limitations so thus back to the coco, but im trying the chunkier stuff as i never really have used it alone and have seen others use it to good success. So figured why not.
But doesn't play well with seedlings starting direct in it, thus the recent change to kinda get a best of both worlds scenario hopefully as its leaning that way forsure when looking at it more specifically.
As for layering sure if it provides a bonus but in micro setups its usually pretty pointless when you actually consider the actual distances were talking about where 1" can mean 20-25% of your pot volume.
So looking back on all the above i use to have a background goal of keeping things as simple but efficient as possible with the fewest add in whether energy or components, and i think i lost track of that during my hydroton escapade. If im not making it easier for myself to grow and or better with very little extra input or changes then im heading the wrong direction.