Will travel to ZRH in a few weeks and I would appreciate some advice on recent upgrade success/failure experiences or simply on how full C is typically. I see NC=0, but as I have a bit of flexibility I was planning to travel on Wednesday to maximize upgrade chances (where at least there is Z9 and seatmap has 16 unassigned seats). Cheapest ticket books into S, but for less than 200$ more I can get rt in W. Should I be hopeful and give UA some more bucks for a chance of clearing the SWUs? SWU thread for success/failure only has one data-point on 2/21 (Monday, success).

Thanks for any suggestion!