Interesting article about moving from ArcGIS to open-source GIS, though be aware in the end this consultant is trying to sell you training.  I would disagree with the author’s statement:

Many people who come from an ESRI-centric GIS education tend to think that ESRI is the standard because it is the most popular commercial GIS software, but in fact the opposite is true. Most open source GIS software will yield the same results because they implement the same SFS geometry model and the same GEOS vector functions. But ESRI software may not, because it uses its own proprietary geometry model and its own proprietary spatial functions.

He does go on the say ESRI’s software has been around a long time and stood the test of time.  I would argue that ArcGIS software IS the defacto standard not only because it has been around a long time AND has kept up with the times AND I have never hit a wall with it when trying to solve a spatial problem, but also because it is pretty much used by almost all government agencies, and if you want a GIS job in government, you better learn how to use ArcGIS software!  As a GIS Manager in government, I would also say that learning how to use open-source is actually not as important than learning a scripting language like Python or a web programming language.  Having programming skills is much more important for a GIS Analyst then knowing how to use QGIS.  Just my two cents worth!  Feel free to comment.

Click below to read the article.