I would like to have the remote option for my Fusion amp setup, should I buy 1 or 2 kit’s?

In theory you can add a remote kit to every Fusion amp. For a stereo setup 9 out of 10 setups will be connected as master and slave, in this case it is not necessary to have 2 remote kits, the master will provide the data to the slave for audio signals and controls. Even in this setup you have the choice of still using 2 remote kits if for example you like to have a LED in both speakers to show activity.