Hi Wings,
There's never really anything to stop you doing what you want
You may get reliability trouble in the communication. (lost frames/intermittent errors)
Also for I²C high speed the bus load is important, otherwise the signals won't be recognized.
If it is for a demo or home use you can try. If it is for production, be careful about analyzing the behaviour accross temperature and voltage to see the behaviour of the MCU and the Data/Clock lines.
I haven't done I²C for a while, but maybe the 400kHz works with additional features the module doesn't have ?
Cheers,
Alban.