I would definitely recommend going ArcGIS for Server: Site Configuration and Administration 10.2, since in Migrating to ArcGIS 10.2 for Server there is too much specific information for 10.0 (SOM, SOC, etc) which are not relevant for you any longer since you have already obtained hands-on experience with 10.1 architecture. However, there is no architectural difference between 10.1 and 10.2, so you should also consider if you really need to go this course 🙂
ArcGIS for Server: Site Configuration and Administration in general gives you anyway a good understanding of the 10.1/10.2 architecture, so worth going through the materials.