Just checked with Genius and was advised that "I can confirm that the M Technology Package is an increased heat capacity of the braking system and the cooling system guarantees a long-lasting high performance under extreme driving conditions (similar to motorsport) (especially in combination with high outside temperatures).
This also includes upgrades for the drive train cooling system and the M Sport braking system."
For £300, I believe that it's worth the gamble.
There's more info in this thread about the US Spec pack which includes an upgrade to the 19" wheels which are standard in the UK:
https://g20.bimmerpost.com/forums/sh....php?t=1602609
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Current: Porsche 718S Boxster. Tesla Model Y Long Range
BMW ancestry: G20 M340i, F36 440i Gran Coupe M Sport, F30 330d M Sport (RIP), F30 328i M Sport / E90 330D LCI, 330D, 325i / E46 325i, 320i / Merc 250 D AMG (listed to remind me never to buy another Merc!)