I have used GRLevel3, GRLevel2 AE, and RadarScope. All three have great uses and tools. One of the best upgrades I've done for GR is to include road names, Rivers and I've added A topographic map for the background.
I have some links and information posted on our MN Skywarn Group on how to add these tools:
Twin Cities Metro Skywarn | Facebook
Here's the direct link to the files and my favorite's link:
https://docs.google.com/leaf?id=0B649YK5IbGEwY2U1NmU3MjAtM2E5OC00MTcxLWI2NjktYjM4MDUwNTI1ZDNk&hl=en
In my own view here's how I look at the three different pieces of software and how they work.
GRLevel2 AE Great a a home based or office based operations because of the need for higher bandwith to update and use all the tools for AE.
GRLevel3 is great for anywhere and also for the beginning user. For in-field use, an aircard will provide enough bandwith to download the radar maps and additional placefiles if you have them added.
RadarScope works great on the Ipad or Iphone and has many of the basic tools for viewing and zooming. This application also interfaced directly with SpotterNetwork to report a position and displays watches and warnings.