First I want to say that I think Mr. Glanville has done an excellent job creating such a powerful, free, stand alone modeling tool.
Since it is free, I tend to think of asking for features as looking a gift horse in the mouth. Think of these more as suggestions for turning the gift horse into a race horse.
1. Target weld for vertices - that way, you wouldn't have to reposition multiple points, and then merge them, and you wouldn't have to worry about repositioning the resulting vertex.
2. Elements only editable for the selected mesh subdivision or spline. ...If you want to use another mesh as a reference, you could select the mesh to edit and modify it's elements, without accidently modifying elements of the reference mesh.
3. Editable viewport background color - sometimes the current color is too dark or the wrong shade to view certain textures well.
4. My last request would have to do with scaling. I tend to use the scaling tool as a last resort, because of how it scales in reference to the object's axis, instead of scaling in reference to the selection. For example, after scaling 4 points, I have to move the points back to their original location. This makes it difficult to scale accurately because I can not scale them in reference to anything, since they move away from any reference points.