Conversely, I'd accept lower pay for 4x8.

I'm close to financial independence and would rather have my time than more money.

25%, I don't think there is any way around that, it seems untenable to have such big difference in rate between employees

I really liked working 4x10 when I was working a blue-collar industrial job over college breaks. It was not union, but it had a similar attitude towards the sacrosanctity of break times, which broke the day up nicely. Clock in at 6:30, spend the first 15-30 minutes going over the plan for the day. Work until 9, then everybody downed tools and took a coffee break. Go back and work until 12:00, clock out for half hour lunch. Go back and work until 3 for another coffee break. Then you'd usually just wind down and pick up until you clocked out at 5.

In a lot of ways, working an 8 hour day as a software developer is more stressful, because it's so disordered and interrupt-driven. Meetings are strewn around all over the calendar, wherever they can best fit the constraints of people in disparate locations. Emails or pings come in with problems you've got to handle right away - and it seems to be easier for people to rationalize making you switch tasks rather than finish what you're doing when you have a piece of software in pieces in your IDE than when you have a bulldozer in pieces with the tracks off...