My only experience with mobile BPs was on a CO flight last winter. TSA was having some issue with the scanner at their checkpoint and basically kicking out anybody with a mobile BP and ordering them to come back with paper copies. Thankfully, I had chosen to use a paper BP and got through without issue. Granted, that wasn't CO's fault (at least, I'm assuming it wasn't on their end) but I would like to remove any chance of there being an issue at times like that. That said, WN needs to offer it as an option for those who are comfortable with it.