System Information
Min 8 Nvidia geforce 560
Blender Version
Broken: 2.72
Short description of error
Whil sculpting I found out, that the grabtool moves the vertices on the symmetryplane faster than the others.
in my opinion the the grab streinght was multiplied, because the mirrored stroke overlaps with the real stroke.
Exact steps for others to reproduce the error
Try to grab vertices that are on the mirrorplane and compare the movement to vertices, who are not directly on the mirror.
It is the case for every brush.
It is the reason why there an option to avoïd this called "Feather" in Symmetry panel.
You may want this behavior to emphasize symmetry plane or point.
Maybe it can be considered as a bad default to have option off but not as a bug.
I experimented with per vertex attenuation for brushes calculated from initial coordinates (other brushes suffer if the fix is applied on them) but the cost is greater and there is no consistently better behaviour. I'd say we keep things as they are now. Probably we can make feathering default for grab, but again, the result is not always nice. So I'll close for now.