I found this video showing live fire trials aganist the Swedish' S-tank during the 1960s /1970s.
http://www.youtube.com/watch?v=MiWCpIJ5dBw
The speaker's voice is in Swedish but translations into English are available.
The tests show that the S-tank truely was a tank that was difficult to destroy and very well could have been the subject of further development.
Cheers, Taskforce