I have not seen a really good direct comparison, but I had a big debate with myself as to whether to buy a D2H- D2Hs or a D2X. After very little thought and research I dismissed the D2Hs as just not being worth the extra UK's £1000. ($1850).
Next I looked long and hard at the D2X and spoke at some length to my agency. Oxford Scientific Films who are part of the Photo Library Group. Now this organisation want BIG FILE SIZES and I thought that they would advise me to buy the D2X. Surprise, surprise thay came back to me and said that there were too many unresolved issues with the D2X and said spend the money on a D2H and wait until at least a year before considering changing up to a D2X. So I bought a D2H from Hong Kong and saved myself £2000. ($3600), an amount of money that is not to be sneezed at.
I apologise for not answering your question about a direct comparison, but hope you find the above of interest.
BW. Bob F.