You'll be just fine with RWD and a good set of snow tires. Mine's gotten me through the last three winters no problem. Your only real problem will be ground clearance.
Oh course, an Xi with snow tires will give you even more traction in the white stuff so if your top priority is snow traction an Xi + snows is your best bet. However, given the extra weight, reduced economy and more parts to service, I'd just stick with a RWD model. Minimal snow traction trade for the benefits of RWD.