I created a scriptlink that is designed to snap verts to a sphere during real time editing.
Algorithm:
If in Editmode:
(1) Leave Edit Mode
(2) Snap Nodes
(3) Update Mesh
(4) Go Back to Edit Mode
The link is executed on ObDataUpdate.
Except for meshes with less than 20 or so verts, Blender crashes when going back to editmode. So the size of mesh may be a key to killing this bug. This bug sucks and makes extending real time editing capabilities difficult.