Your project is by no means going to exceed the DVD with iDVD.
If you access to Compressor or DVD Studio Pro (uses Compressor), you can recompress your movie to maximize resolution. You can set the program to build the project several times until it maximizes color depth and resolution.
Side note, the difference (one of many) between Criterion and SuperBit DVDs is the compression. Criterion editions add all sorts of extras. Extras take up space and decrease the available space for the primary movie. SuperBit DVDs remove everything extraneous, including unnecessary languages, subtitles, features, and sound options. I think I see the and hear the difference. But hen again I work with media and can tell the difference between somebody dropping a pen, penile, or ruler while listing to an audio scrub. A perfectly useless skill.
In the future if you have a really good project that starts with great resolution remmeber that you can