The trial was for 68 employees and cost $1.7 million USD (they had to hire additional staff). Imagine you took that $1.7m and spent it on those 68 employees. $25,000/employee would go a long way to increasing happiness with perks etc.
I'm more in the latter camp and my colleagues and I have been talking about doing 4x 9.5 hour days and just rotating who gets Friday's off vs the rest of the week. I could easily come a bit earlier, leave a bit later and get tons of benefits from 3 day weekends.