Superfluous RAM use hurts battery life a lot. Using Safari over Chrome easily saves 2+ hours for me.
Do you have a reference for why this should be? A quick search yields results suggesting only the opposite (for instance, https://superuser.com/questions/738848/does-more-ram-usage-c...).
That said, eventually both get to 6g of ram in use and a restart is needed anyway.
Cheers!