Currently on the Settings, options, Quick Defrag tab, if more than one box is ticked it means ALL those options must be true for any file to get defrag'd.
How about the ability if ANY of the options are true, those files will get defrag'd.
For example, Have more than: n fragments and Are larger than: n MB only defrags those files that satisfy both choices.
Maybe the addition of a selectable AND / OR between each option so you could have Are larger than 10 MB OR Have more than 10 fragments.