If you have control of the content, then using a touch more compression on your media may be preferable, or you can scrape a little extra with overburn - or 90/99 minute media, if your drive supports a large enough overburn.
Mode 2 is non-trivial - you need extra filters installed to view some content ... the "correct" way to author a Mode 2 "XCD" is to put any Installable or data critical content in FORM 1, and only audiovisual media with error handling in FORM 2 ... the error handling of many formats in these conditions is not certain (and by HANDLING, we're looking for the ability to continue with a minimal glitch, or preferably conceal it - eg blanked audio instead of a loud pop)
If exploring methods and techniques is part of the project aim, then exploring and understanding the risks and rewards of Mode 2 would be good, but if you want a bit more capacity without too much fuss, go with a little overburn, or the extra length media.