Bruce:
Thanks for your reply --
actually the limit is in the thickness measurement, not the deformation. You can recreate the thickness files with mris_thickness -max $maxthick ... if you want a larger value. What's going wrong?
Well we're trying to guess why the pial surface is somewhat consistently (across subjects) positioned short of the actual pial surface in certain instances, notably frontal medial temporal, and some other locations.
We had wondered whether it was because of such a limit.
Graham