The Docomo model has Band 17 which should cover me in most areas - honestly, after testing a friend's LTE capable phone, I didn't see a big difference in browsing or app speed between HSPA on my Docomo S4 vs their LTE model and I don't typically download content to my phone - although LTE might help with up-syncing files from the phone to dropbox, etc.

Something tells me they won't post the whitepapers for the Docomo or KDDI models - in essence, I am trying to figure out what might be different (ie better) on the Japan models vs the global models. My Japanese S4 has a better processor, sturdier glass and was made in Korea vs the lower quality Chinese factories - that last point alone is enough to steer me to the Docomo model.

However, if they are all made in the same place and the the only real difference is Docomo bloatware+Felica+long waits for firmware updates, then I won't bother with the Japan model as I can have do-it-your-self Felica by sticking a plastic SUICA card in the back of the case and installing the SUICA account app on the phone....and the rest of the "features" are useless to me anyway.