Yes, Screenmode prefs in 3.5 and up has a test feature. To test modes on my older systems I actually use Overscan prefs - the Esc key works to get out of modes that don't work. It doesn't have quite the level of versatility as Screenmode prefs, but if the base mode works in Overscan prefs, most of the variants do as well.
Also take a look at MUI 3.8's PSI (Public Screen Inspector) tool... that might suffice, too.
