Yes, front wheel braking, whether friction or regen, is more effective and stable than rear wheel braking.
Skidding the rear wheels under braking is a good way to spin a car.
Like blogspot said, traction and stability control should prevent rear wheel skid.
My earlier remarks were about getting stuck in the snow, I hadn't even thought about front vs rear wheel regenerative braking.
When traction is so bad as to be a safety issue, I'd want to shut off regen and use only well balanced four wheel friction brakes, but that's not possible with a Spark, is it? I think you can do it with a Volt by putting it in Hold mode.