Spell Catcher X 10.3 works around the bug in Mac OS X 10.5.x (Leopard) that made it necessary to deselect “Make replacements directly (without backspacing) where possible” when using Spell Catcher X 10.2.3 on Leopard.
Mac OS X 10.4.x (Tiger) users - Spell Catcher X version 10.3.1 fixes the problem with this preference when using Spell Catcher X 10.3 on Tiger.
So by all means, we encourage you to select this preference, and (once again) take advantage of the performance improvement that direct replacement can provide.
In general, this would be procedure:
In the Spell Catcher application, choose Spell Catcher > Preferences.
If necessary, click the Applications icon to open the drawer with the applications list.
Select the “Universal” item at the top of the list.
Click the Interactive icon, view the Typing tab.
Make sure that “Make replacements directly (without backspacing) where possible” is selected (on, checked...).