I'm currently ussing 8.1.7.0 Global Stable ROM and SOT is not that bad. I tried 7.4.27 and SOT was very bad. I was loosing 1% of the battery every hour, without doing anything, in standby. When I sent a message, i would lose 1-2% of the battery. So now I'm back to 8.1.7.0 stable, and SOT is about 5-7 hours.