I can't comment for sure as I haven't done a comparison between spray on vs sheets. I have used stinger roadkill expert and dynamat extreme throughout my car so far:
I'd suggest looking up some car audio forums (eg. caraudio.com, sounddomain.com, caraudioaustralia.com/forums etc) and do a search there as the car audio guys will have a much greater knowledge of such products and may have done some comparisons.