I have both 2009 SHM-CD releases, WPCL-10697 (English version) and WPCL-10698 (Japanese version).
The Japanese version definitely sounds better, musically, than the English version. Much brighter, crisper and cleaner.
So much so, I searched the internet for the reason why, which brought me here.
FWIW, the mix is not different. In other words, the English version is not a "Rough mix" or "Remix" or "Leathur" version i.e. some of Motley Crue's stuff with different instruments and/or tempo and/or effects.
Only the finished production (mastering) is different.
REALLY wish the English version sounded as crisp.