Makes sense to me. The obvious flaws in "fleece" over windshell are wind and moisture. In terms of wind, I have always tried to approach this with a lower CFM garment than the wind layer, but not so high as fleece. What I am starting to suspect, though, is that this deficiency is not nearly what one might assume. Yes, the wind can cut right through it and steal trapped warmth, but that serves to dry it too, and the wind layer underneath guarantees that you won't feel the "flash off" due to evaporative cooling, since it happens on the outside. In a driving consistent wind, it still seems like super high CFM materials like fleece may allow too much airflow, and all the heat you put there is immediately stolen. But in most wind situations, I am wondering if the drying affect offsets the temporary heat loss, which the heat of the consistent engine underneath the second skin quickly replaces.
The second flaw, moisture, is the one that is currently the topic of heated debate at SD. For me, though, 99% of the time the issue is moot, since a base layer/wind layer is all most folks ever need in above freezing temperatures when on the go. Then when they stop, say at 35 degrees, they can just put on a down puffy for the rest session. So the wind wear is always on the outside during a light rain event. But in colder temps, or lower exertion activities, external moisure is the issue. To me, the best way to deal with this is to use uber light storable rainwear that you use ONLY when it is raining or otherwise introducing external moisure (bushwhacking in wet brush, etc.) Just like the Cloud Layering System. This works regardless of the air permeability or water resistance of the outer layer, in all situations. The problem is that this TOTALLY kills the system by putting a 0FM low MVTR layer on the outside. The two ways to solve this are to find high CFM layers that have significant water resistance (so far, I have come up with nothing there), OR to make that "rain layer" have a high CFM and high MVTR (as GoreTex, Event, Neoshell etc. try and fail miserably to do). But there is another way, that while not perfect, is the best way that I have ever found to stay relatively dry hiking hard all day in the rain. Don't rely on the breathability of the fabric, rely on airflow UNDER the fabric. Like a tent. But not all floppy like a poncho. To me, solving the ultralight rain piece allows the rest of the system to work. But ONLY if you accept the premise that this goes on in the wet and off when its dry, and the rest of the system works independently. That challenges the "push the wind wear into light rain" point of view. I can see the benefit of that point of view on a day hike. But while backpacking, I am a believer that you need good rainwear, so to me that system is the best way to stay warm and comfortable at the lowest possible weight in any conditions, which is pretty much the goal of mostly everyone, except the extreme who don't care about comfort and are just pushing for survival only.