I just purchased a Diehard Platinum based on searches here. From what I understand it is a re-badged Odyssey. This is also what the tech @ Sears told me. Plus you cant beat the warranty.
Two good threads on this subject -
http://www.expeditionportal.com/forum/showthread.php?t=14285&highlight=platinum
http://www.expeditionportal.com/forum/showthread.php?t=33581&highlight=platinum
I have Sears Die Hard Platinum in my Frontier. It will be the battery that replaces the one in my wife's Xterra when it goes bad.
And you only have to drive to South Aberdeen for warranty :snorkel: