I have been studying the LOPA of the A350-900 presented at the Allegris launch event and have plotted the seat map. It wasn't easy absorbing the nuances and intricacies of the business class seats but I think I now have the measure of it. Curiously though, the Businss Plus seats appear to have about the same square footage as the First Class seats although within their footprint the BP seats do include footwells belonging to the seats immediately behind. Of course, while mapped from LH's own LOPA, the seat map is subject to change.
Zoom in of the premium cabins