Yes it’s a tough one indeed. Basically, Apple states that under normal use one can expect 9h approximately, heavy use would of course be. less? Would you say your 6-8h is with heavy use ?Regarding battery life - which for many is the biggest sacrifice in downsizing - I have been getting 6-8hrs SOT in my daily use. Pretty happy with it, coming from a 15 Pro Max.
Can’t help comparing with my 14PM, but need to accept it’s apples and pears. Spec-wise they’re not so far apart though…