Mine has always been great in the snow. I've had weight in the back as well as running empty and haven't noticed much difference (I've always run soft tops).
Tires will make more of a difference than anything else. I'd be a little concerned about the locker. I've never run one in snow for that reason.
On ice, all bets are off. We get nasty ice storms every few years and it's never a good time. That being said, I still prefer the Jeep for ice driving.
“The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed.” ― Robert M. Pirsig, Zen And The Art Of Motorcycle Maintenance: An Inquiry Into Values