QGIS this year split into two branches:
Latest release (now 2.10.2)
Long term release (now 2.8.2)
I am not sure how is it normally in larger companies but I think having (hard)core GIS employees who need to work with OSGeo4W version and GIS users who are fine with standalone version is not that rare. And if these two groups need to work on the same projects they need same versions of QGIS.
That makes the GIS employees need to have either two versions (OSGeo4W 2.10 and standalone 2.8) or possibility to be able to downgrade with OSGeo4W to long term release version.
Is downgrade with OSGeo4W to long term release possible somehow? At this stage I have possibility to only downgrade to 2.10.1 in the advanced installed list.
Best Answer
Using advanced install of the OSGEO4W installer, you can choose the package
qgis-ltr. This will bring you the long term release qgis 2.8.x.QGIS 2.10.1 and ltr can be installed together (same as QGIS and qgis-dev can). Double-clicking on a project file will open it with only one of them. You can change the version with doubleclicking on
C:\OSGeo4W\apps\qgis\bin\qgis.regorC:\OSGeo4W\apps\qgis-ltr\bin\qgis.reg.BTW, I would suggest to use the standalone installer for larger companies, saving download time down to one single download. Standalone versions go always into different folders, hence can live happily together on your hard disk.