I used to use another aplication for keyboard and mouse sharing called sharemouse for multiple years, and it has suited me very well.
i could use my laptop mouse in my desktop and my desktop keyboard in my laptop without having to switch the primary and secondary everytime, because it was automatic.
I moved to Multiplicity because of its audio sharing feature that i couldnt find working this well in anywhere else, but it doesnt mean that the application is perfect.
the drag and paste option appears grayed out and i cannot do anything about it. also, as i said, i have to manually switch in between my primary and secondary, while it could be automatic.
also, as i use the steam version, everytime i try to switch the primary and the secondary, steam automatically closes one of the applications, and it causes the programm to not authenticate, so i have to restart both computers.