I do this, and I'm pretty sure it's common.  Building JCMs into conformers, since the actual rotation values of the conformer are not changed when the conform target is posed, the JCM is never dialed up if it is hooked to the conformer's rotations.  (Note: I haven't retested this in Poser 8 but I think it behaves the same way.) Instead I have a dial on the conformer's BODY that hooks to the conform target's particular joint rotation, for each JCM; and then within the appropriate bones in the conformer, those are hooked to the conformer's BODY dials.  Is this clear enough?  You can look at some of the freebies I've done to see how I do it if you want an example, e.g. this one:

https://sites.google.com/site/fleshforge2/Home/free-stuff/encounter-v4

The boots have a JCM for each foot, which applies a morph when the foot is bent to prevent pokethrough.

Quote - When I conform multiple cloths to a figure, the superconform of morphs often doesnt seem to work any more (in P7).

If you make certain to select the conform target each time you load a conformer piece, you shouldn't have that problem; the whole process is exploiting a semi-bug "crosstalk" and behaves consistently if you make certain to re-select the conform target, even in a scene with multiple conform targets.

My Freebies