Hi Adrian,
It certainly is an interesting design idea.
My original design is meant to cut down cost and complexity, so if another design meets those criteria, then I'm all for it. The original design is meant to passively hold in moisture and the neoprene sleeves are cheap and easy to use and should help create a tight seal to lock in moisture.
Rockwool might be interesting for a drip system, but I have only ever seen them sold in tall, angled cubes, and I'm not sure the geometry of those would lend well to a design like this, unless you plan on changing their shape. But a drip design is interesting. One problem with some of the other designs is that they lose water too easily and dry out, so a drip system might theoretically work better in that regard and have a higher success rate.
I do not currently have any equipment for drip irrigation, so for me, and at this time, that adds undesired complexity and cost. However, if you think the drip design would work well for you and you have the equipment to try it out, then by all means test it out and report back later.
