Using D to allow air resistance and friction to slow the car instead of regenerative braking to the same degree is an illusory benefit. The energy lost in slowing is just that - lost. When you want to resume the former speed, you have to expend the same amount of energy with either method. The difference is that, with regen braking (however slight), you put something back into the battery.
If you want zero regen, i.e. "gliding", you need to find the amount of accelerator pressure which neither draws power from the battery, nor returns it. This comes instinctively with practice, and is the ultimate in one-pedal driving.
Provided your control of the accelerator is sufficiently sensitive, you are better off in B. But the difference is probably so little that you may as well follow your preference (or prejudice).
My second car is an old Toyota RAV4 with 4 speed auto transmission, which gives gliding in 4th (overdrive 3rd if you wish). Frankly, having got used to the SoulEV, it's a damn nuisance. I would much rather control retardation on the accelerator pedal.
As for paddle control in the new Soul EV, I don't want it. I see it as no better than having to select O/D OFF or L in the RAV4. B Mode is perfect for me.