I have purchased and used both Instant Copy 7 and DVD2ONE and in my opinion...
In my experience the DVD2ONE rules when doing full movies backups because I have never had a bad backup with it ie quality of the finished film, its never aborted and its very fast.
In the case of Instant Copy 7, yes its easier and faster than doing a movie backup the OLD way, but its a very unstable program.
I've had it abort with no error message when it was the only thing running and more frequently when I attempt to carry on using the pc for my normal work.
I do like the fact that it can also be used to create VCD's & SVCD's from dvd's as I have a NAPA Portable MP3/VCD Player.
dvd95copy & dvdshrink.
I've never needed to use either of these so cannot comment on them.