Is a free newspaper and guaranteed sitting for 15 minutes instead of maybe have to stand for 15 minutes worth the extra money? Buying discount tickets online saves a substantial amount if you guy up front or with the Duo Saver.
I guess if you're traveling solo and didn't buy a ticket up front, it's only 5 quid or so difference in ticket prices between saver and standard, so buying standard to get the upgrade is probably worth it.