I'm going through my HD DVD collection and collecting the details of each disc. My findings so far:
The largest HD-30 disc is Dreamgirls (Disc 1 Feature Film) at 29.94 GB.
The smallest HD-30 disc is Happy Gilmore at 16.23 GB.
The largest HD-15 disc is The World's Most Beautiful Places at 14.75 GB. The largest film HD-15 disc is ATL at 14.15 GB.
The smallest HD-15 disc, by far, is HDScape Sampler, at 5.37 GB. The smallest film HD-15 is Army of Darkness at 11.82 GB.
The largest DVD-9 combo disc is Hot Fuzz at 8.53 GB. The Kingdom is 8.52 GB.
The smallest DVD-9 combo disc is The Lake House at 5.82 GB.
The largest DVD-5 combo disc is TMNT, and is 4.66 GB.
The smallest DVD-5 combo disc, by far, is HDScape Sampler, at 1.97 GB. The smallest film DVD-5 combo disc is The Reaping at 4.55 GB.
The majority of films on combo discs are HD-30/DVD-9. There are at least four HD-15/DVD-9s (16 Blocks, ATL, Kiss Kiss Bang Bang, The Lake House), one HD-30/DVD-5 (The Reaping), and one HD-15/DVD-5 (TMNT).