I read the following article and was wondering how those slim tiles would perform in NZ conditions (ie timber frame, moving with various moisture loads, particularly radiata pine).
From my experience, the thinner the tiles, the better the substrate has to be.
You have less tolerance to play with ie mediating substrate unevenness.
They have less strength to deal with weak substrate.
Funny thing is NZS3604 where you cannot exceed 12.0 kg/m2 per side of wall for wall linings (plasterboard plus tiles) unless it becomes specific design. (NZS3604 12.1). Well, plasterboard has already 7.6 kg/m2. A 10mm tile can have up to 26kg/m2. Installing any of those will not be covered in NZS3604, OVERLAYING them with slim tiles does not make it any better. It you plasterboard is substandard fixed, if might just fall off the wall. I personally do not think that adding tiles won't work, but it may not comply.
Therefore I rather only agree with the last bit in the article: They reduce loading – but only if you do not overlay.
Traditionally, wall tiles are much thinner and not that strong anyway – I remember something like 5-6mm. But whether that knowledge is around – NZ is not exactly a tile country.
I have used 6mm tiles for walls, for floors I would use stronger ones, 9-10mm, they can cope with substrate unevenness, weakness and mortar application inconsistencies. If you have the perfect substrate and believe you do the (almost)perfect job, then go for thinner ones.
I would not overlay as you are multiplying the (potential) problems outlined above.