The main reason is that I only want to take ony full-size keyboard to a showing, so it will always be the hard choice whether to take the BK-9 or the Yamaha MoXF. Yesterday, for the first time in 8 weeks, I played on my MoXF again and realized that even if the keybed is less weighted than the BK-9 one's, it responds better to dynamics from pianissimo to fortissimo, which is important for classical piano tunes like the Chopin.
In addition, my arms don't bear the operation with the click wheel pressing very well. I still have my BK-7m, so I've come to the conclusion that for the time being, MoXF plus BK-7m is the better way to go, with the additional option to think about buying Varranger, as I already own a Microsoft Surface Pro 3.