Any titling that you make in FCP will be permanently embedded in the finished video.
Do it in DVD SP with a text file made in TextEdit. Give your viewers the option of turning it off.
Stolen from the DVD SP User Manual...
Preparing subtitles for use in DVD Studio Pro:
> Note: If you specify a font to use, no subtitle
clips will appear if the font is not found on the computer that will be encoding the DVD. The font must be installed as a Mac OS X font— Mac OS 9 fonts are not used.
Sample formatting:
$FontName = Arial
$FontSize = 24
//If you need to include comments, place them on their own line, preceded by a forward slash, a space, then another forward slash like the example here. This text will not be superimposed over the video.
00:00:12:04 , 00:00:14:12 , This is a subtitle...
00:00:16:14 , 00:00:19:08 , ...followed by another subtitle.
//Comments can also be placed between subtitles.
00:00:22:08 , 00:00:26:15 , This is the next subtitle.