Shou sugi ban will out last any other naturally durable timber cladding in New Zealand. This is because we only use species that are recognised as meeting the New Zealand Natural durability standards (Minimum durability of 3). By charring the timber we improve the durability of those timbers further.
In terms of expected years in service for charred timber, the proof is found in the 1000s of old buildings clad in Shou Sugi Ban all over Japan. Many examples can be seen that have over 40-year-old charred timber cladding and are still strong and weather tight.