Been stuck with open diff 4x2's, open diffed 4x4, locked 4x2's and locked diffed 4x4. Most to least in that order. ALL rigs will get stuck. Question is how bad.
I've also use tire chains on all 4 options, towing and non towing. 9% grade is pretty small, had to go up some in the 20-30% relm. Snow and ice covered will not be JUST a 4x issue. Many times one need chains in addition.
With that said.....for most of the driving I do, a lock rwd, will work fine. Yes 4x is handy, but even then, a locked diff helps in that setup too.
Marty