I haven&#x27;t worked on the project for a while. I pulled up the 2011 survey report at <a href="http:&#x2F;&#x2F;www.ks.uiuc.edu&#x2F;Research&#x2F;vmd&#x2F;survey&#x2F;report2011&#x2F;vmdsurvey2011rep.pdf" rel="nofollow">http:&#x2F;&#x2F;www.ks.uiuc.edu&#x2F;Research&#x2F;vmd&#x2F;survey&#x2F;report2011&#x2F;vmdsur...</a> . There were 56,575 registered users then.<p>Mind you, I don&#x27;t know how many of those people write scripts. Plus, VMD also supports Python, though that was added years after Tcl.<p>Personally, I think Tcl is better for the types of scripting that the physical scientists (biologist, chemists, etc.) - most of my user base - want to do. However, as something they developed became more generally useful, I found I couldn&#x27;t easily tweak it to be part of the larger system. OTOH, while Python is more complex than Tcl, I rarely feel the need to rewrite user code in Python into C++ code, so there&#x27;s a more smooth transition between non-programmer code to experienced programmer code. That is one of the reasons I switched to Python.<p>On the flip side, IPython and others have developed script-like meta-languages which makes it easier to do some of the things that Tcl excels at.