A lot of times I can’t use the the axis as reference because it is hidden by the geometry. I have tried the useful grid file from Marcus but it seem has the same problem, even it is a lot better. For example for the case of checking if the central points of a model are aligned exactly in the center of the axis. I can’t see the axis because the geometry obstruct it. Then I need to find workarounds like looking in the edges of the model etc that makes things messy.
Any solution for this?
There is the ‘Dots Display’ mode which renders the selected subtool as dots when you move/rotate it. Turn on the Dosts Display button (which has a cube on it, next to the Solo button) in the Transform palette. However, I did notice that ZBrush could become a bit unstable on my system, so be wary.
If you are checking the position of subtools relative to each other then the Position sliders in the Tool>Geometry sub-palette may be useful. These give the actual positions in world space.
What I was trying to do is to restore the symmetry of the central line of verts. Smart sync does it in everything except in that point. Then the only way is moving manually the verts but I can not know what I do if I can not see the central axis. I guess the dots display is only active when the viewport is movement, then not useful for editing unless you know other way.
With sophisticated low poly tools as the zmodeler it is odd there is no way to see the central axis in all views as it behaves as a 3d object and it is obscured by the subtool when overlapping.
This little plugin might be useful:
http://www.zbrushcentral.com/showthread.php?193480-pls-help-how-to-send-vertices-to-zero-position-on-an-axis
Extremely useful plugin. I have the central verts continuously messed by external programs.
I check periodically the plugin section of the forum and I didn’t see this one. I wonder if would be perhaps useful if you list all your plugins in one thread in the plugin section and add any new plugin there. It would avoid to miss any of your useful plugins. If I want to know how many and which plugins you have done I can not really tell.
There’s this thread which is where I generally put stuff.
http://www.zbrushcentral.com/showthread.php?172391-Useful-small-ZScripts-and-Macros-for-ZBrush-4R6
I’ll be creating a new thread for 4R7 plugins when I have time.
That one is not there. 
Anyway thanks for your plugins!