AFAIK, true statement.
IIRC, engine friction is dependent upon fluid dynamics (micro oil film on reciprocating engine parts) so friction is reduced even if the stroke is increased. Furthermore, longer stroke engines can be more efficient b/c take longer to go from TDC to BDC so they extract more of the combustion force and they don't push expanding gasses out of the exhaust port.
Here's the tricky part, imo. Torque = force x radius so if you add 10mm of stroke, you're adding a lot more torque. Sounds nice, but wheelie control is already working overtime to rein in the 800s. If the bikes are more prone to wheelie, they will be slower for two reasons. First, wheelie control is cutting additional power to counteract the additional torque. Second, the engine takes longer to extract the combustion work so it doesn't rev as freely and it may even accelerate a bit slower than an 800 or a 900 with the same bore. They can shift more weight over the front to keep the bike level during acceleration, but I think that will lead to handling problems.
The 81mm conundrum has been analyzed by Ducati who claim that 900-930cc is the optimal range for an 81mm MotoGP engine. Imo, it is the displacement at which Ducati is comfortable with fuel consumption and valve surface area to cylinder displacement ratio. It probably allows them to run the engine wide open without worrying about engine reliability restrictions. It's a mess.