DSC will be a good save for you in snow, i wish i had it. but in times when you are stuck , and the wheels wont turn because of the DSC than of course take it off. This will usually only occur on steep snow covered hills.
as for the rattle, pinpoint the rattle and then you should get back to us. get a buddy to sit in the car, opposite backseat and then between the two of you , you can pinpoint a general area.