It seems to me the whole point of the 3-piece vs the 1-piece was that the thermally induced expansion of the manifold (proper), was such that it didn't match that of the head, and resulted in broken flanges and such. Doesn't the stock/OEM manifold have elongated bolt-holes in the flanges as an attempt to accommodate the expansion?
I also think the metallurgy alloys used to make the new 1-piece manifolds have greatly diminished the issue. Perhaps in better matching the expansion characteristics of the thing. I dunno. We'll eventually know from those who go that route.
I've been running an ATS 3-piece for the last five or so years (I think, maybe longer).
As far as heat control, I've always run the ceramic coatings. A so-called
thermally reflective ceramic coating on the inside of the hot-plumbing so as to keep the heat in the exhaust gasses in the first place. Then there's the
low thermal emissivity ceramic coating on the exterior of the hot-plumbing so as to help keep the heat in the iron (thus helping keep the gases hot). My compressor housings are coated with a
high thermal emissivity material to better shed the heat of compression. (Looks like black paint to me.
)
It seems to me though, that with the thick heavy castings of the assembly, that the benefits of the insulation blankets/coatings doesn't really do anything for us in short-lived WOT bursts ref: Drag-Racing for example. My thinking is it takes time for the heavy castings to saturate with the heat and wouldn't loose a lot in the short run.
- Thin-wall manifolds would be the glaring exception to the above. There, the insulation would be VERY helpful in keeping the heat in, in the short-run.
That being said, the insulation still helps a little in the long-run as an improvement in overall thermal efficiency of the engine.
So say the voices . . . . or, at least three out of five . . . tonight . . . . .
. But again, even if there was, it wouldn't mean anything. Just like turbos.... flow is not everything 
