I'm a previous Retrospect user, and I switched to SuperDuper! after I heard tha EMC was killing the Mac version of Retrospect, and a lot of research on SuperDuper!, ProSoft's and Intego's options.
I'm very glad that I chose SD! and for anyone that cares to read the Retrospec article, here it is:
http://www.theregister.co.uk/2007/01...rospect_eight/
Yes, I know it's not 100% confirmed, but I'm still glad that I switched to SD!