Windows 8.1 Impressions needed (mainly battery life)

[skinnie]

Hi guys,
I am thinking of upgrading to windows 8.1 (clean install) on my X230.
I've been reading about it, specially battery life and all websites shown much less battery life.
Do you think in 2014, after so much bios and driver updates it is solved or it is still better to stay with windows 7?
Anyone tried Windows 10 preview?
I have msndaa account of my university so any MS OS is free.
Thank you all