When I was buying my used Jet 1336 the owner said it had CXA tooling, and I thought he was probably mistaken. At least I was hoping he was mistaken because the holders are almost twice as expensive as BXA. Sure enough when I brought it home and was checking everything out the holders were CXA (250-301). I had read Matt's article about measuring, and the comment about "approaching 2" stuck in my mind. Not having a BXA to set on the lathe to compare, I'm now glad it is a CXA because it fits perfectly and it is robust.
I do have a shim under the mini lathe QC holder that I have on my old Atlas 12", and I can't say it hurts a thing using 3/8 carbide tooling.
Dan