If it works for you great but the theory behind it isn't due to any magical properties of DriClime. Use any cheap synthetic garment with decreased air/vapor permeability. A garbage bag full of holes would work the same way.
Not that I'm aware of. FWIW, Durable Water Repellent (DWR) causes water to bead on the fabric's surface. It doesn't significantly change the fabric's air or vapor-permeability (unlike a PU coating or other form of "membrane"). The fabric's tight weave is what does all the work.
The tricot lining is to absorb sweat and spread it out over a larger surface. It's very permeable to air and moisture and provides some insulation. The moisture is ultimately absorbed by the outer polyester layer where, in contact with air-currents, it evaporates. That's the operating theory of two-layer DriClime and VR garments. The outer layer is wind-resistant but not wind-proof. In other words it's both air and vapor permeable but far less than say the tricot. Twight is leveraging the outer layer's lower air/vapor permeability to act like a substandard VBL. Any tightly woven synthetic garment will do the same thing.
"Not very wet at all" In other words, not really dry either, huh?
DriClime is vapor-permeable. Your body's moisture
is passing through it and into other layers. If that layer can lose the moisture through evaporation then it'll feel dry. Otherwise it won't. That's why Twight is saying to wear outer layers that allow the moisture to evaporate. You're still moving sweat through all the layers you're wearing. In my opinion, slowing the rate of vapor transmission is, frankly, of dubious merit (stopping it entirely, like with a VBL, has greater benefits as does accelerating it).
Did he explain what else he tried and why DriClime worked best? For example, did he try a VBL? Or just a cheap nylon windshirt? Or did he just try this and nothing else?
If by "breathes" you mean
vapor-permeability then no it has limited influence on heat retention. If by "breathes" you mean
air-permeability then yes it influences heat retention. High air-permeability allows for convective cooling and accelerated heat-loss. Fleece has high air-permeability and that's why it feels chilly when windy. In comparison, an eVent or Gore-text jacket has near-zero air-permeability but comparatively high vapor-permeability.
Anyhow, I suggest you look for a cheap nylon windbreaker ... or just pick up a spare DriClime jacket the next time one comes up for sale.