cool, they finally got there
im not so sure its 'approaches', as being being a down to the physical nature (and implmentation) of the expressive controller.
relative is often preferable, where the Y axis on the controller is small, i.e. you cant really start in a definite Y position (think Roli block/linnstrument), or the mechanics of the controller e.g. eigenharp (discrete keys) /seaboard rise (piano layout), make it preferable.
however, something like the haken continuum and Madrona Labs Soundplane which have a larger and full continuous Y axis, absolute feels much more relevant, so you can start the sound wherever you want it to be.. i enjoy this a lot
but as such, all this should be hidden from the sound generator... the point of 'mpe' is to present the controllers in a unified way... so basically as a continuous x/y/z surface, its then up to the controller to allow different 'modes' if necessary e.g. absolute/relative.
anyway thats how i work it... i write patches as if the surface is completely continuous, so they work well with my Soundplane, but they also work well with my Eigenharps... even though they are quite different.
that all said, i find is you always end up 'refining' patches/presets for the specific controller. I'll often find particular patches which i really enjoy on one controller are pretty 'average' on others. its to do with how they play/feel - I put this down to the fact the response rates / sensitivity which really vary between controllers.
(this is a point Ive heard Haken/Eagen make, that to make a really good expressive patch, it needs to be closely tied to the characteristics of the surface, then it feels 'natural')