Yes,the Fantom can run 16 external midi channels/Devices via the Midi out as well as its own internal 16 timbres and Expansion tracks and 24 Audio tracks.
With such a great seqeuncer on board,not sure why you would want to use an external device for such a task,unless you have something better like an Akai MPC or Roland MV8800,or you prefer to use Software instead,the Fantom G sequencer is probably the best on any Workstation for what its allows you to do and compose with even if it needs slight improvements.