For a while when I first purchased the L1011 I was looking for a replacement to the INS due to the time it took to program, and then again for the CS 727.  Finally after several unsuccessful attempts to create a FMC, I one day started working with Flight Sim Commander and there I had an epiphany! 
In the real world I was a Army Pilot and except for a short period of flying a Scout Aircraft, all the rest I flew were 2-man crewed cockpits.  One flew the other navigated, so if you have the luxury of a second monitor and you have FSC do you flight plan on it, take-off, and once established turn on your autopilot with heading switch on, then engage the FSC autopilot.  There then is no difference to the real thing as far as shared work load.  On my system I have my second monitor to my left, so I watch my progress, see the nav aids and tune them in, and when it is time to fly manually I have my map still there for reference just like I would before GPS and FMC's.