Yeah I went from 2014 to 2017, and went from broadly not worrying about doing 6 hours of solid dev work without thinking about battery to essentially never feeling comfortable away from a plug.
I'd guesstimate I get at most 3 hours on the 2017 before the battery level gets low enough I have to start planning where I'll next plug in. Not ideal.
Many people would describe an hour's difference to be a "significant" change, especially when a scale of around 10 hours total battery life is being considered.
Sure, but considering the "fudge factor" that Apple often applies for their battery life estimates ("casual browsing", etc.) an hour isn't all that much.
I'd guesstimate I get at most 3 hours on the 2017 before the battery level gets low enough I have to start planning where I'll next plug in. Not ideal.