I only use the Iowa State feed to download L2 data ad-hoc. If there is a severe outbreak (or something else of interest) I will go to the URL and find the radar site and time of interest and just download the files. Otherwise, I pretty much use AH all of the time for live polling. What I can tell you is that during the last outbreak, back in February, the Iowa State site would not let me navigate to the L2 data via the URL in a browser. I don't know if it was down or if they were just locking people out of doing ad-hoc downloading or what. You are probably better off getting the AH subscription.
And yes, GR2Analyst is a must have for those wanting more than just L3 data.
Also, keep in mind that the Storm Hunter subscription from AH comes with a license to use GREarth as well.
