"is this "Change over" from one effect to another in sequencer mode a fairly straight forward procedure?"

If you're just pressing buttons on the front panel as your song plays, then it's, well, just that easy.

If you want to do it automatically in a song, you have to use one sysex message.

If the XV5080 has a Transmit Edit function (I assume it does; I think the XP2080 has it, too), that function will generate the sysex message for you.