right on. tegaderm and clones are a semi-permeable membrane like goretex-allows vapor to pass, but not water droplets. Put it on a wet wound-road rash or similar abrasions, you get a layer of serous drainage, blood, pus.], that collects under the teg and stays wet and eerily squishy for a long time (experimented on myself, and one of my kids). put a piece of gauze on a dryish wound, add a teg to cover it, and you have a pretty cool dressing, protects the wound from water penetration and permits it to breathe.

The hydrocolloid dressings are an outgrowth of burn center technology, but they are heavy and bulky and offer little first aid advantage over gauze squares, as nearly as i can tell.
On the other hand, if you are using maggots for wound debridement , colloids might work fine:
"What is the role of hydrocolloid dressings in maggot therapy?
Despite decades of experience in Maggot therapy, selecting appropriate dressing materials continues to be a problem. The dressing has to (1) prevent the maggots from escaping, (2) permit oxygen to reach the maggots, (3) facilitate drainage, (4) allow inspection of the wound, (5) require minimal maintenance, and (6) be of low cost.

One centre developed a two-layered cagelike dressing, the bottom layer of which comprised a hydrocolloid pad, applied to the surrounding healthy skin and covered by a fine chiffon or nylon mesh. Liquefied necrotic tissue drained through the mesh and was absorbed in a top layer of gauze, which was replaced periodically. Thus it was possible to contain the maggots within the wound by means of readily available materials.

Reference: Sherman R. A., A new dressing design for use with maggot therapy. Plast Reconstr Surg 1997 Aug;100(2):451-456"