I'm not overly enthousiatic about these "paper de-rating" solutions. The OEW / fuel burn / production costs / MRO won't decrease.. maybe (engine) MRO a bit.
It's still a big long haul airframe. But if the tax is better it makes sense.
Depending on the engine, and magnitude of the de-rate, can make a significant difference to engine maintenance plan prices.
Also airport and other weight-related fees, and potentially CORSIA-related costs.
As long as the option to re-rate exists, and is not too costly, seems like a good plan. Secret is to lock re-rate prices (often more than one option) at time of purchase.