I'm trying to do some brainstorming, here. 

Is there theoretically any way to winnow the proper tripoly or polygon out of the point-cloud returned by the range of closest vertices influences?  If so, can the equivalent of a hitpoint on that tri or poly be derived in any way from the final position represented by the collection of weights?  I doubt the precision of raycasting could be recreated this way, but the best candidates among the returned variable might be able to be derived.  (I guess this idea sort of bleeds into the last one listed, below....)

I've discarded any kind of closest polygon approach to all of this, because it seems like it would involve too many additional distance calculations, with polygon incenters and then the vertices of selected polygons.  But perhaps something in that area could be used somewhere in a process to get results.

It occurs to me that the .vmf data can be trimmed or screened using the tools in the Morph Trimmer script.  This could offer a decent tool set to enable the combining of select areas of different comparisons.

Are there any user-definable variables which could be used to help improve raycasting?  All I can think of would be a cutoff threshold to block bad matches and possible alterations to the normals before running the process.  Part of what makes closest vertices more accessible, IMO, is that there are more potential parameters which can be altered to try to improve results.

While considering hybrids, why couldn't we cast a ray between the original Target vertex and the weighted position found for it using closest vertices?  That ray would intersect a tri of one of the vertices with which the current hybrid code can work, in the current form.  Is there any reason that a ray cast along one normal is better than another?  This approach might generate a tri correlation which is more likely to be compatible with any averaged results from closest vertices being used in neighboring areas of the mesh.

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Cage can be an opinionated jerk who posts without thinking.  He apologizes for this.  He's honestly not trying to be a turkeyhead.

Cage had some freebies, compatible with Poser 11 and below.  His Python scripts were saved at archive.org, along with the rest of the Morphography site, where they were hosted.