I've only ridden my BionX equipped bike (added last Nov) a few times so far between snow storms. I've found that its torque sensor rewards me more the harder I pedal thus I'll put in more effort of my own to reap the benefit.
In the past I'd twiddle up the 2 mile hill up to my mountainside NH house at 5 mph in fairly low gear, 32x34 or 22x34 on a bad day. If I worked over twice as hard in a slightly higher gear I'd be going maybe 8mph. No return for the effort so I'd go back to the 5 mph and arrive home without even breathing hard. With the electric assist I can ride 10-15-20mph (if I'm feeling spunky) up the same hill in the big chain ring, 44x13 or 15, and arrive home winded and exhilarated. That reward is like a carrot out in front that makes me work harder with the assist than without. Thus I've checked the 60% box above.
This is at the fairly high "mountain mode" assist level on the hill. Normally I use the 1 or 2 assist levels (out of 4) in more moderate terrain.