Saw a FB post on Brother hobby's page about the new larger 2mm magnets on their motors to replace the 1.8mm, does bigger magnet mean more power?

Larger magnet don't necesary mean increase in performance. Firstly they are heavier, and secondly there is a possibility that thicker magnets can create parasitic drag from eddy currents that aren't present in the lower field density of the smaller magnets.

Also the larger magnets significantly sharpen the cut-off for prop loading tolerances. On the thinner magnets, when you start reaching the limits in terms of prop loading (or overloading as the case may be) the motor just starts loosing RPMs and current stays fairly constant past a certain point, since the motor is struggling to push the prop.

With 2mm magnets, the motor just keeps on pushing and draw massive amount of current! But news if you plan to over prop these motors. You'll see your battery life plummet and the motors will get hot pretty quick if you're reaching the limit, so something to keep an eye on if you've got the 2mm version. The T2 will have the usual 1.8mm magnets, which I think is a better idea for an all-around motor.

I think arc (curved) magnets and line them up closer can actually contribute more towards better performance than using larger magetns.