I believe training to grass is a far better preparation for what you might be faced with in the real world and the ability to reduce groundspeed to a minimum is more likely to lead to a successful outcome if you end up having to do an EOL onto a less forgiving surface.
I realize the proverbial horse is probably beaten only a few atoms thick at this point, but...how does training to grass promote proper groundspeed at touchdown? Is that not the job of the instructor or check pilot to pass/fail the pilot on groundspeed at touchdown? Because you don't want the surface handing out any failing grades!
I've found the ability to hit my spot to FAA commercial standards (+/-50ft) to be very confidence inspiring. But I don't practice EOLs to the local pub parking lot (although if it were for real that might come in handy
).