I find suma can effectively show most kinds of data. As long as you make clear the analysis was done volumetrically and how you mapped data to the surface, it is fine to display results with suma onto some standard surface. Note when suma talks with afni, the overlay in the afni GUI is sent to the suma GUI and colors the surfaces. By default, that coloring is done just at the intersections of the surface nodes with the volume. The Vol2surf plugin in afni gives controls that are similar to the 3dVol2Surf program, and offers a variety of ways to more effectively show data from within the volume onto the surface - like reaching into the volume to find a maximum, minimum, mean or median. Also regarding the other direction of mapping data from the surface to the volume (on the command line only), the program, 3dSurf2Vol, and the script, @surf_to_vol_spackle give a multitude of choices.