I could be perceived as biased since I'm the CTO of Evolved Analytics (www.evolved-analytics.com) and wrote much of the DataModeler code over the past 13 years, however, DM is probably the most efficient, complete and powerful symbolic regression platform out there for any environment. In addition to the basic model development, it supports the entire workflow from data exploration to model analysis and insight generation.
The industrial and corporate analysis roots of DM run pretty deep and the continual enhancement draws upon our ongoing project efforts. It is not "freely available"; however, the academic and commercial licensing rates are very reasonable. We also offer two-month trial licenses (but you have to provide your own copy of Mathematica) for those interested in putting it through its paces.
There is quite a bit of information available at the website as well as papers and tutorials on industrial data modeling which we have presented at the major evolutionary computing conferences for those seeking more information.