My understanding is that Sport mode just alters the throttle pedal movement to power relationship, There is no magic, other than that it feels very powerful but the same acceleration is available from the normal mode as you point out.
The same applies to 'L' mode. It gives no additional regen to that from applying the break pedal to get the same level of retardation. My understanding is that the cars disc brakes are not activated until the asked for retardation exceeds the regen capability at a particular road speed.
I like the sport mode for the feel it gives, but I only use the 'L' mode on steep downhill events, just **** using a lower gear in a manual transmission with an ICE.
